Braxton hicks

I got in a minor car accident yesterday i was in the back seat my back was instantly in pain and has been ever since i had just left the parking lot of my ob and went straight back just to check out the baby they used a doppler and said all was fine last night i think i was experiencing braxton hicks my stomach was tightening up about 3 times in 20 minutes i was able to fall asleep so im assuming im okay can braxton hicks have a pattern