Braxton hicks or??

No pain, only that "tight" feeling I usually get but I've never had them this regular before. Noticed them at 5:30 on the dot, decided to keep track for shits and giggles. Was NOT expecting they'd keep coming. At the 6:04 one I decided to go for a walk, and literally just walked back in the door at 6:35. I've been drinking water all day. When do I call the doctor? Add another contraction at 6:37.