Small armpit lump

Hi- it’s been over 5 years since my diagnosis. A few days ago, in the shower, I noticed a small hard lump in my armpit (cancer side). I had several lymph nodes removed, so I don’t even know if it’s possible that it’s a node. It’s a little sore, and the whole area feels a little swollen, but I don’t know if that’s just because I keep poking it.

I already had an appt scheduled with my PCP for this coming Monday (12th). I will definitely ask her about it. Should I call my onc too?

I haven’t been sick or anything that would make a swollen lymph node make sense. How worried should I be?