sounds like gastro mate. I get that sometimes also. I was a sufferer of IBS so I know the symptoms very well and the feeling sick part is usually the first sign that something is in there that wants to come out in a hurry. Its a horrible cramping feeling that can often be all over the abdo (up high and low) as well as the back. Once the pressure is relieved by either passing it or passing wind the aches will start to back off. I used to suffer with the bowel spasms for hours later even after the problem had resolved itself. That is when I used to take buscopan but your not supposed to take that while pregnant.

A warm shower or heat back on your lower back might help relax the bowel as well as a couple of Panadole. And rest up, relax and don't panic.