Awww hun, that really sucks.

Don't worry about your gastro affecting the baby, my best friend had bad gastro when she was pregnant and her Dr told her that her body will take over and provide nutrition for the baby when she was really sick. Our bodies are amazing things, especially when we are pregnant.

As for taking something, I'm not sure. I'd definitely talk to your Dr or midwife.

Hugs
Sue x