Lump under armpit

So, I noticed a small lump under my left armpit 4-5 days ago and it hurt really bad to put any pressure on it or touch it so I decided to go to the doctors to get it checked out( I'm only 20 btw) I'm a hypochondriac so I instantly wanted to know what was the issue. My doctor examined it and said it looks like hidradenitis suppurativa which I guess is a bad chase of cysts/acne that can be extremely painful, but after going to the doctors the first lump went away and a second one showed up right under the first one (same armpit too) so I decided to go to a dermatologist today and he examined it and asked if I've been sick recently, which I was back in early March. He said it looks like a boil or cyst that should go away with antibiotics but I declined taking them because I usually always get yeast infections from an antibiotic so he prescribed me a topical antibiotic. Hopefully it'll help. My question is... If the lump goes away after the antibiotic should I still go to the doctors and get a mammogram done or cancer screening? I'm still young, yes, I know age doesn't matter. But I would rather be safe than sorry. Thanks for taking the time to read this😊