Hard lump in armpit

Last night i had a sore spot in my armpit when i moved my arm around and sore to the touch. It wasn't too bad but throughout the night i kept waking up because i was so aware of how sore it was and it increasingly got worse over night. By the time i woke up, it was painful. I could barely move my arm around without pain....not soreness, pain. It is coming from one hard lump, about the size of a little marble in the middle of my armpit. It hurts bad to the touch and hurts in general when i move my arm around mixed with soreness. When I'm sitting still i can feel the lump and i feel slight tingles through into the side of my boob.

This has never happened before so I'm a little concerned. At first i thought it was just a pimple or ingrown, but to be honest i haven't shaven my armpits in about a week because i planned on waxing them, and i just shaved to see if it was an ingrown and it wasnt. And I've had pimples once before under my armpit but it wasn't like it....it was more topical. This time around, you can't see anything on the outside of my armpit skin. I only feel it on the inside.

I'm still hoping it's just a pimple.....if It does go away this week than i will see my doctor on Friday. In the meantime, I'm just curious if anyone else has had something like this. I'm not freaking out yet, but i am still keeping an eye out.

Oh it also hurts when i just have my arm hanging down like normal