Bleeding & Cramping @ 34 weeks

I am 34w5d and have been bleeding (not spotting) and cramping. The bleeding is like a medium amount not heavy but not light, enough that i am filling light pads. The cramping is a constant ache and then gets more intense. I went in to labor & delivery and so far they cant figure out whats wrong their best guess is the start of labor. So they sent me home on modified bed rest and if gets worse to come back in. Just wondering if anyone has experienced this and has any advice or anything?