Should I be worried?

I'm exactly 33 weeks today. It's 12:18 AM and I'm having really bad cramps that do not go away and spread to my lower back and butt bone. I've got a heat pad on my lower back but it has not helped neither does laying in a different position. These pains come and go and get a bit stronger as time goes by. For the past week or so I began to get Pelvic pressure and my little girl has dropped quite a bit since my last doctors appt. Doctor also thinks I will deliver early since my mom had my two brothers and I 5 weeks early. I have my hospital bag ready I just don't know if I should be worried about heading to the hospital quite yet.