My armpits are sore and I feel like I ve been on crutches. It looks like there is a slight lump, a little more clearly on the right. A lot of people said it could be swollen lymph nodes or a sign of breast cancer but apparently, both of those would be noticeable a little lower than where the pain/lumps are. About a week ago my grandfather helped me check the fluids in my car, but I didn t have a stick to prop the hood up so I held it up with my arms. First my right, then my left... the same order in which the pain appeared (a few days ago). I work 6 days a week, normally on drive thru, and I suspect that I might have made it worse by sticking things out the window and lifting my arms to get drinks to fill and dump ice in the fountains. Is there a likely chance I could have just damaged a tendon in my armpits? The fact that it s both of them makes me think that might be the case, but I m not a doctor so I don t know if my thoughts are right on that or not...