Lumps in armpit.

I've had this happen a few times since I was a teenager. Recently I've been getting them a lot. Much larger and painful. They are under the skin and very annoying! I had a baby 2 years ago and currently pregnant so I'm wondering if this could be why?

People have told me it's normal and others say it's not! I also have painful boobs 😩 where do I get this checked out?