Unexplained Abdominal Pain

Clare • Age 26. Married. 👦🏼😇😇😇🤰🏻
I'm just over 18 weeks and went to urgent care last night for some ongoing abdominal and upper side pain, as well as nausea, constipation, and blood/mucus after a BM. I tested negative for a UTI and my ultrasound looked fine. They felt around the sides of my belly which was tender to the touch and sent me home without any conclusive diagnosis/treatment. I asked if it could possibly be gas and they said it could be but there's no way to test for that without doing an MRI (in the emergency room) to look for gas and/or an intestinal blockage. After leaving I drank some seltzer and had a few good burps (sorry for the TMI) and have been using a hot pad for on my side for some relief. Any ideas? Similar experiences? I have been crying out of frustration and impatience for this to go away. So uncomfortable and scared b/c I don't know what's going on! (I have a history of Crohn's Disease.)