Constant cramps

Has anyone else experienced this! Started yesterday as light period cramps and has not stopped. I don't think it's Braxton hicks because they don't come and go but are more consistent. I'm 31 weeks and went to l&d last week for unknown bleeding and everything looked perfect. I spoke to my doctor a few hours ago and he said it could be my uterus stretching etc however I'm getting no relief from the pain. It's just constant. Drinking Water doesn't help, nor does a bath or changing positions. Not sure if these are contractions (like I said they don't come and go but are constant) and it feels like I have my period. Could it be a stomach virus? Anyone else go thru this? Thanks!