What's going on?

Rayyy • Due end of April!
I was up all night with what I thought was a tummy ache with maybe gas, etc. 
I'm pretty tired. 
Now I'm feeling more like contraction-ish pains. 
I just stood up and felt like a decent amount of discharge. (Sorry tmi- but like when you're on ur period and sleeping with a pad on and you stand up.) 
How serious is this? 
Can I wait to call my OB on prep in 90ish min??
I'm 24 weeks and 3 days.