Pea sized node in armpit. 2nd time i've seen it in last 2 months. goes away on its own in 1-2 weeks. painful upon palpation. lymph node? cancer??

Axillary node: This could be lymph gland responding to an inflammatory stimulus or a sweat gland plugged with oil, getting inflamed. Get it checked

Probably OK: If it goes away predictably in that time frame, it's probably a normal, i.e. reactive lymph node. If it ever persists beyond one month, you should just have it removed for formal diagnosis.