Pre term labor???

I'm almost 23 weeks pregnant with twins and My stomach keeps getting hard (while standing, sitting, and lying down) I have back pain that comes and goes and pressure down below (as if I have pass gas but no gas) and really thick snot like discharge and I keep getting a feeling like I need to go #2 but it comes and goes, is this a sign of pre term labor? Wondering if I should go get checked out. I can't see my Dr until June 11th