Trying to figure out if I'm starting to go into labor. K and I just got home from a VERY bumpy off…

Trying to figure out if I'm starting to go into labor. K and I just got home from a VERY bumpy off road drive. On the way home, my back started killing me and I had a few harsh times where there was pressure in my bottom. I didn't feel the need to push but it feels like I need to toot or something. I have now been in a warm bath for about 15-20 min. The back/ bottom pain keeps coming back ever so often and goes into my thighs it feels like. And just now, I felt a little sharpness in my vag area.... Think these are beginning of contractions?