Contractions? BH? Back pain?

I'm 34 weeks and 2 days. Since this morning I have had the worst cramping feeling. Feels like bad period cramps. And lots of back pain with it. Occasionally I feel tightening at the same time, but not always. I have also had mild loose bowel movements today. And some fatigue feeling is my upper thighs, like when I'm on my period. Are these contractions or Braxton Hicks or stretching or maybe a stomach bug? Please help! All advice is welcome :)