Contractions? 29 weeks pregnant

I have been having Braxton Hicks on and off since about 25 weeks. I am not at risk for preterm labor. Today I woke up feeling off. I am having period like cramps that wrap around to my lower back. They are stronger than Braxton Hicks I’ve felt before. I stretched for about an hour and went on a walk and they still seem to be coming. The problem is I can’t tell when they clearly start and stop. I have work later and will be on my feet for over 8 hours. I’m not sure what to do?