In some serious pain

Kristel
38+6 and since 1:30pm I have been having period like cramps and some back pain. It's now 9:38pm.
The back pain comes and goes without warning but the cramps have been constant with only a few minutes of relief.
I've tried glasses of water, sitting, standing, and walking. Nothing makes it go away. I'm about to try a hot shower/bath as my last resort. 
It's now the worst it's ever been and baby moving makes it feel like my pelvis is going to split open.
What's happening to me?! Any advice on how to make this stop?
Tylenol hasn't been working since 2pm.