Hey this is my first time posting on here and I was wondering if I should be alarmed that my gecko has really big arm pit bubbles. I just noticed them today. He’s never had them in the 6 years I’ve had him. When I press on them they disappear, so it seems they have air in them?
I’ll send some pics
Welcome to the forum! Feel free to make an introduction post in the ‘Introductions’ section if you have the time, it’s always cool to meet new fellow herpers. 
Armpit ‘bubbles’ are actually a fairly common issue in leopard geckos, and there’s no need to panic. They are not full of air, but rather fat, fluid from the body, and deposits of minerals.
I am not aware of anyone writing in an academic journal regarding the cause of the armpit bubbles. However, among hobbyists, they are generally thought to result from one or more of three possible factors:
Because your gecko is 6+ years old and has not had them previously, genetic factors are less likely to be the cause. The next thing to rule out would be obesity. Is he overweight or has he recently gained weight? If not, then you more or less have to assume that oversupplementation is most likely.
In my experience, oversupplementation is most common in leos that are older (like ~10+ years) and/or male. Geckos that are no longer growing, and that do not form or produce eggs (males/older females) have a reduced need for calcium. Excess D3 forces calcium absorption whether the gecko needs it or not.
It is very possible and actually fairly common to give overdoses of calcium/D3 when trying to get the right balance when it comes to dusting and gutloading prey. It’s important to consider a bunch of factors that come into play when figuring out supplementation for every leo individually, so any simple/ one-size-fits-all schedule (e.g. ‘only feed __ and __, use gutloading formula xyz for _ hours before feeding, then dust every _ days with _’) is generally not sufficient to get things just right. For example, supplementation levels for breeding females during the breeding season should be much higher than for elderly males.
Factors to consider:
What I suggest in the case of your little man is to try slightly reducing the level of calcium in his diet (not overall nutrients, just calcium & D3) and observing for any change. This could be accomplished a number of ways, and the best method will vary depending on your feeding & supplementation practices.
To reduce calcium in the diet (always be gradual!):
If you try those methods and there’s no change with the ‘bubbles,’ honestly it’s probably fine. If the bubbles start growing or looking unhealthy (e.g. a color change), then it’s time for a vet visit with a reptile specialist. Bloodwork will help determine exactly how high your little one’s blood calcium levels are or are not, and you could make adjustments based on the super accurate info. If you are extremely concerned, you could get radiographs taken, but in almost all cases it appears that the armpit bubbles don’t cause problems.
Example:
I currently have 2 geckos with big armpit bubbles of my own.
Anyways, I hope my opinions might help get some ideas! Please keep in mind that I am just one hobbyist. If you happen to know several veterinarians that are ABVP-Reptile & Amphibian boarded AND have kept multiple leopard geckos for at least 10 years, definitely give their opinions heavier weight than mine. 
Thank you so much for all this info!
I don’t think he is overweight because around 60 grams last time I weighed him. (Which was a week ago?)
I didn’t realize too much calcium/vitamins could cause this. I recently added a calcium bowl into his tank so that might have been the cause. I will make sure to keep an eye on how much I dust his crickets and his armpits. (And remove the calcium bowl)
Again thank you so much for this info! I was a bit worried lol
One of my breeder females had this. She had some egg-laying problems a while ago and lost a ton of weight, so I was trying to get her fattened up before breeding season (this was last year, I wasn’t breeding her, but I didn’t want problems if she went off food again). I fed her heavily dusted mealworms as a staple for a while. She gained weight and also developed bubbles exactly like in your picture. I cut down on the mealworms and dusted the food lightly (I used dubias as a staple), and now they are basically gone.
Ohhh ok that’s reassuring! I’m glad your gecko has gotten better
Update: it has almost completely disappeared!!
Hey! What ended up working for you? I have a leopard gecko who I got as a supposed Juvenile (looked like a baby). Her name is George (I named her before finding out the sex lol) and she has grown pretty quickly (I’ve had her for 5 months now). Obviously I could be over supplementing as I use calcium with d3 (i do not have a uvb bulb). She loves licking up the calcium and I know leo’s are supposed to be self aware and lick up supplement as needed. I feed her every three days and she eats a lot, but I don’t believe she is over weight! Also I am very afraid to under supplement, unfortunately years ago I was ill informed on taking care of a leo and we didn’t supplement him until it was too late, he suffered from MBD and his legs got wiggly and he ended up being put down as he was just shrinking and getting worse and that tramagized me a little! Any suggestions on what I should do for my leo? For reference the first pic is the day i got her the second is about a month ago!
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