Hello everyone, please advise — I'm 21 weeks pregnant. Earlier I had l…

Hello everyone, please advise — I'm 21 weeks pregnant. Earlier I had lower back pain; it was painful to roll over and bend, I thought my sciatic nerve was pinched. Now the lower back pain has eased a bit. At the moment I have tolerable but unpleasant pulling pains in the groin area, I can feel them even when walking. And at night my belly has started to feel like it's tingling. Are these signs of increased uterine tone? I'm afraid it's something serious, I'll go to the obstetrician tomorrow.