I've had that too but only a few times. Not sure if it was period or "O"
related though. It was my armpit and felt like about 2/3 inches down the underpart of that arm too. Luckily I've read that it's all normal. Not
sure what causes it but definitely the least of my meno symptom worries right now.

Donna

I had underarm pain (in both armpits) that would come and go for about 3 weeks. It was right after my period. This was the first time I ever experienced it so of course I googled. Im not sure about the period connection (sense I was over my period I didn't google about it) but what I did learn was you have lymph nodes under your arms so if you have any infection, cold, whatever they can swell and cause pain. other causes of pain is a nick from shaving, a hair follicle, new deodorant or your skin rubbing due to no deodorant. I was surprised by how common it is. I think mine was due to my skin rubbing. I was trying to get away from the toxins in deodorant and trying some natural ones, which took awhile to find a natural one that actually works. Most of all that makes sense to me, but I would never associate a cold with armpit pain.

I used to get underarm pain as well right before the period. This concerned me so I saw the gynecologist. she told me that the under am is actually a "tail for the breast." Therefore, if your boobs swell up or are cystic (mine were) the underarm will accumulate alittle fluid and become tender.

this should subside after the period. Also always check for lymph nodes when doing month breast exam

I don't have specific armpit pain but ever since going into perimenopause I have had body aches like no tomorrow. They have definitely cramped my style and I feel so utterling useless. Everything is a chore for me and I have been in the dumps and in a "mood" recently and it is just no fun.

Have you had a DEXA scan? Could be arthritis. I have it. Comes hand in hand with deficient estrogen.