When sitting, i feel nauseous when there is pressure on my right grasilis muscle. (no pain) i didn't pull that muscle not that i know of. no lump there. what would cause this?

I would think that it's crunching your abdomen while sitting that could cause nausea and not pressure on your inner thigh. Apparently your thigh isn't tender& there is no evident superficial phlebitis there. I assume the nausea is relieved by standing up. Has a physician examined you for this symptom and suggested any testing? ? A pelvic examination by a gynecologist with attention to the groin.