Stomach discomfort driving me insane - anyone else have this?

I'm 4w4d today and I have the weirdest discomfort in my lower abdomen that is driving me bonkers. I wouldn't describe it as cramps and it's not even really painful - just this dull, constant discomfort. It's in my stomach, too, not my uterus. I had a tiny bit of dark brown discharge last night and this morning, so I rushed to the doctor this morning without an appointment and begged them to check my labs again, which turned out to be absolutely fine. My hCG had more than doubled, my progesterone was up and the doctor said everything is looking great. But it's still stressing me out. My first pregnancy ended in MMC at 8 weeks and I don't know how I'm going to make it through this pregnancy without actually losing my mind.