Early labor?

I’m 25 weeks with twins. I’ve been having Braxton-Hicks since 18 weeks and am used to the pressure without pain.

Today though, I went to work and after about an hour and a half I started to get this unidentifiable nauseating squeezing. My back was aching and I had to go to throw up a little. Sitting or standing didn’t make a difference.

I had a bit of a break during the afternoon though I still felt rough. But it’s ramped up again, this time my spine feels like it’s getting wrung out to dry and my stomach is rock solid no matter how tired and shaky I am. It’s shivering through to my legs almost like my period cramps do.

Normally I would call the midwives to ask but I had to be in hospital 3 days ago for another reason and was having braxton hicks so much they decided to check my cervix; high, firm, and long. So I don’t want to seem stupid by calling so soon to ask if I should be worried.

Am I seeing things that aren’t there? Am I just being a drama queen?