Pain through vagina. maybe labor? tmi

I'm sorry if this is tmi but randomly i'll get this pain through my vagina. Like all the way through it. 
I'm 21 weeks. I do have a subchronic hematoma and bleeding. I'm at risk for preterm labor, placenta abruption, and i did lose my mucus plug. 
I will be calling the doctor. But is this normal? A sign of labor? 
With my first baby i didnt feel contractions at all, so im worried i wont feel them again. Also, i do have back pain as well (Middle of back). I dont know if labor in your back is lower, middle, or high