Ok I noticed this a couple weeks ago but did not worry because I couldn't feel any lumps or pain under my arm. The thing is its just puffy. When I press on it it feels like fat. It is noticeably more puffed up than the right armpit. I am wondering if they are swollen lymph nodes, but don't see how it could be when im not feeling any hardness under the skin. I am 35 weeks pregnant and don't know if that has anything to do with it. I plan on asking my doctor but was wondering what you guys think. Thanks in advance.