BH or real contractions!?

I'm almost 31 weeks along and have had Braxton Hicks on and off since maybe 20 weeks. They where rare and no pain, and never lasted long. But for about a week and a half, more so the past two days, My whole tummy gets rock hard and I feel mild cramping pain in my lower stomach. I timed them, and they're definitely irregular, from 11 minutes, to 7 to 4 all lasting about 20 seconds each. Are these still BH or could it be real contractions?