| | Large lump in upper arm muscle; what is it?!
Allow me to preface by saying that I am a 20 year old female, I do not work out, smoke occasionally, do not drink, come from cancer-ridden bloodlines, have had a weakened immune system for the past few months, and have not been bitten by any insects in the past couple months.
Earlier this afternoon (around 5 hours ago), I noticed a large firm lump on my upper outer right arm. It's about the size of an egg, was (and still is) warm to the touch, and was accompanied by skin redness at the time I found it. The redness subsided in approximately 2 hours. It is on the firm side, and I'm not able to move it around. It noticeably protrudes from my arm, and seems to be attached to my muscle. It seems like it's applying pressure to the muscles/nerves in my arm, because my right hand is very unsteady.
When I run my fingers over it, it feels round, hard, and stationary, and is a bit tender.
I did not notice this just a couple of days ago, it's like it just appeared out of nowhere. I had no trauma or injury to the area, so I have no idea what brought this on.
I was reading into rhabdomyosarcoma since it was one of the first results I found when I initially Googled my symptoms, and it seems to fit. I'm just hoping I'm wrong.
Any help or input on this is greatly appreciated.