During Pregnancy I Developed An Umbilical Hernia But My Ob/gyn

During pregnancy I developed an umbilical hernia but my ob/gyn didn't seem concerned. My baby is now 5 mos and I had all hut forgotten about it, since it wasn't protruding or anything. Ever since I had my galbladder removed I've gotten horrible gas pains but they always pass fairly quickly. However twice in the last 2 weeks I got excruciating stomach pains (that I thought were just gas pains) and right above my belly button began protruding out and became hard as a rock and very very painful to the touch. I tried going to the bathroom and of course nothing happened. Both times, it lasted about an hour and a half to two hours before the pain, and knot, subsided. I had completely forgotten about the hernia before this. Could this be the result of a hernia? If so, is it something the doctor would be able to diagnose/see even if it's not protruding/flaring up?