I had that too at the beginning of my pregnancy and was also on anti nausea medicine. Also prenatal are constipating as well. For me a heating pad worked wonders. I was also told to take a miralax until I finally went and then switch to stool softener which I could keep taking until when I went it was more of a peanut butter consistency (sry gross I know). I am not comfortable taking lots of medicine especially lots of different ones so I did do miralax but never did stool softener once I went. I did really feel tho that the heating pad and lots of tea and water helped me go.
Its probably gas. Drinking warm fluids helps with constipation. Like hot tea. Im not sure whatto do about the gas, its normal as ive read but ridiculous