Help! Don't know what to do!

Last night I started having real bad back pain and some stomach. I figured since I'd been on the go all day that's what it was. When I got home I had a warm bath and it helped a little. I went straight to bed with it hurting here and there. I woke up and it was still hurting some. I've stayed in bed all morning and that's all I've had off and on is back and stomach pain. It's not consistent enough to be preterm labor so they'd just send me home if I went to the hospital. I'm holding out till tomorrow since I have a doctors appointment anyway. The pain is just getting stronger some. Any ideas? I'm 32 weeks and 4 days. Could it be preterm labor? I haven't had any blood or mucus with my pee so I think that's a good sign? When should I booket to the hospital if it gets worse before tomorrow? First time mom and very confused...