Am I having contractions?

I’m 37 weeks pregnant and I have been getting sharp pains across my back and hips. It’s like a band going from one hip, across my back and into the other hip. These sharp pains build to a climax each time and are painful enough for me to have to stop what I’m doing and hold my breath. I’m not feeling anything in my front, or not a lot anyway, and I know for a fact you can get contractions in your back! I’ve experienced this 3/4 times in 1 week (first time was last Saturday) and tonight’s were pretty painful!!

Has anyone else experienced this? Did it turn out to be contractions?

I’ve already lost my mucus plug and do have other symptoms that point to early labour. My Midwife says it sounds like I’m in early labour but I’d like to know if these are contractions or something else. TIA