Well, I dont have a penis, but I do have an abdo with crohns! Lets see, if it is a pulled muscle, you should probably feel the area hurt ( i suspect especaially with a sharpish pain) if you intentionally move that area and put it under some mild strain. Try lying down and lifting both legs, one leg at a time into the air off the floor. See what happens in particular when you lift the right leg. When you stand up, try bending over to touch your toes and then straighten up and stretch with your hands in the air and whilst standing on your toes. If you stretch this area and it feels sharp but relaxes when you relax then maybe it is a pulled muscle. You did only go to the gym 2 days ago so it could be it. On the flip side it could be a sign of crohns activity. Go with the muscle for now and see how things progress..I guess you will soon know if its crohns pain.
If the bowel activity hasnt done anything different since the pain developed - hopefully you just need to rest that muscle a bit!
37y/o female from Australia
Dx: chrones April 2010
Meds: Currently : prednisone, calcium