Strange skin bump/growth—anyone seen this before?

I noticed this yesterday—honestly, I hadn't even thought twice about it before. I’m not sure what’s going on, so I’ll be heading to the doctor (actually, I am planning to go), but I’d really love to hear what you all think. It’s actually quite tender to the touch, which is weird because it just showed up maybe a week ago. Usually, I’m pretty observant about these things and would have caught it immediately, so I'm genuinely stumped. What could this be?

Here are some photos:



It isn't quite as large as it looks in the picture; the diameter is probably only about an inch or two...

It’s located on my side—not directly under my armpit, but further down, somewhere along the midsection between my armpit and my hip.

Ethan Martin said:So, I noticed this yesterday—honestly, I hadn't even thought twice about it before, maybe I'm just oblivious or something, but I'm definitely gonna hit up my doctor, though I'm super curious what you guys think! It actually hurts when I touch it. It showed up maybe within the last week, and if I weren't so clueless, I would've caught this way sooner, seriously. I have no clue what this is??

Check out the pics:



It’s not quite as huge as it looks in the photo, probably like an inch or two wide...

It's located on my side, not right under the armpit, but lower down, somewhere in that middle zone between the armpit and the hip.

Looks pretty weird.
Go see a doctor.