What to do ...

I'm 35w+3d with my Di/Di twin girls.

I've posted this In a few groups not just the Twin one :)

Since about 7pm (U.K. Time) I've have a constant dull back ache + my stomach feels insanely tight, every now and again I get a cramp type feeling but that's only happened once or twice in the past 2 hours. It's mostly there all the time doesn't come and go. I also have shoulder blade pain in my left shoulder - random?! I almost feel like my stomach is so tight I feel like I'm holding my breath & tensing it? But I'm not. I also feel like I've got some sort of dull acne radiating to my hips and the tops of my legs at the front. I've not had any braxton Hicks at all with this pregnancy but from what I remember with my son it doesn't feel like them anyway but also doesn't feel like labour - although my contractions with my son happened because my waters broke first. So I didn't experience any build up with my son it just happened. My girls are kicking but ones been a little quieter this past day - the one who's "Twin A" and on Thursday I was told she's very, very, very low down. I also feel sick + have a slight headache but nothing major. I feel like I have bad period pains and I feel like I need to go for a poo, but like I'm gonna have the runs type thing but I either just go normally or I don't actually need to go...

I'm just wondering what you ladies would do? I'm always handing out advice but I'm crap at taking it lol.