Small painful lump under left armpit

[WinterOfOurDiscontent]

Noticed this today. I'm going to make an appointment to see my GP but if it's painful and in my armpit, is it more than likely to be a blocked sweat gland or something than cancer?? I'm breastfeeding as well, so could it be a blocked milk duct?

Obviously nervous about finding a lump.

I have had something like this twice before. I didn't think too much of it until I started to get flu like symptoms and went to the doctor to be told that it was an infection of the hair follicle(?). Soon cleared up with some antibiotics.