I am not pregnant but TCC so I hope it's ok I respond in here but had almost identical symptoms last month, including reacting badly to small amounts of chocolate and other seemingly random foods. I also had blood tests, a stool test and ultrasound but it all came up clear. So still a mystery. I'm taking probiotics, the ibs probiotic plus mintec before eating (i have never been diagnosed with ibs but decided to do an ibs diet just in case) and it's under control though I still get discomfort after some meals. It seems to dissipate faster and not be as painful too.

So no advice from me except I empathize!