what muscle would make it hurt from my right *** to under my arm

[boocavishious]

what muscle would make it hurt from my right *** to under my arm , it hurts to breath or sit or even to get up I have to get up the nerve to kinda roll over first.  here is what happened - I had to get into my attic so i got a ladder but it was not tall enough but I was able to use my arms and pull myself up and get my legs up around a beam, that was fine but then  getting down was questionable so going down I raped my arms around the wood beams and attempted to lower myself where my toes could touch the top of the ladder, I was in a hurry and what ever I pulled hurt a little at that time but its been 3 days now and the pain has got increasingly worse to the point its difficult to even breath, what the hell did I do ? and how do I fix it ? , I am 53 and am aprox 175 lbs (about 50 lbs over weight) and I use to think of myself extreamly strong with lots of upper body strength . any info as to what I did and how to fix it please would be greatly appricated thanks.

[Paxiled]

I don't know how this could have happened, but the only time I've had these symptoms was when I was doing martial arts and someone would mash one of my ribs.  All this, particularly the pain in breathing, is a sign of rib pain.  It could also be partly an oblique strain, as it seems to be going up your side.  My guess is, this is a strain that will pass from overstretching.  Pretty impressive feat, though.

[gymdandee]

It could be  any of the following! nerves, bones, muscles, tendons, ligaments or joints. Underarm pain is often the result of traumatic or overuse injuries. Underarm pain can be mild, moderate or severe, depending on the cause of the pain and the extent and the type of tissues affected.

The brachial plexus is a network of nerves that travel from the neck through the axilla or armpit to the upper extremities. Brachial plexus injuries occur when these nerves are stretched or torn, which may happen when the shoulder is forcibly pushed downward while the head is pushed up and away from that shoulder.Common symptoms include pain or discomfort under the arm, arm numbness and weakness on the affected side, and decreased motor control in the arm or hand.
You didn't say how long ago this happened. Have you used heat and ice?
If it's just the same then see your Dr.