20 weeks with twins and light cramping

Miranda

I'm 20 and 2 and have been having off and on cramping all day. not like contractions but cramping. it kind of feels like Braxton hicks but I feel like it's to early. I went to the Dr 2 days ago and babies where fine. heartbeats 139 and 135. I've been so tired and having a hard time doing anything. Do you think I should be worried about the cramping or no?