Is this premature labor?

I'm not yet 34 weeks and earlier I had a horrible cramping pain in my back that spread to my stomach area. It lasted for about 40 minutes, going on and off in irregular time periods. 5 hours go by with NO pains and now I'm feeling the same pains. I'm nauseous, and was on the toilet with diarrhea. A few times the pain has a piercing feeling for a few seconds, then leaves and my stomach is aching like period cramps. I was told it's just Braxton Hicks and to not worry but I feel like I'm gunna throw up and miserable and wondering for your opinions? 😓