Ok, so we adopted two sows at the beginning of July. Lovely wee things both of them. They have put on a bit of weight but I probably over feed them. 
Tonight one of them is behaving oddly. She is drinking lots, (I started a thread a while ago because neither of them ever went near the bottle and I was worried) She is lying on her side outside of her wee hidey house and every 30 secs or so, her belly sort of spasms.
She is also starving and hoovering up the dried food she doesn't usually bother too much with.
She hasn't eaten anything new that could have disagreed with her. What on earth could it be? Should I call the vet?