Braxton Hicks?

Could be braxton hicks, although since the frequency is 1 in 15-20min, I would watch and see if the frequency increases (eg. 1 every 3-5minutes) and the pain intensifies. Also, check for other symptoms like show (red mucous discharge from the vagina), leaking liquor (water leaking from the vagina/gush of fluid). Only then would you need to go to the hospital

Use a contraction timer to time them. If they’re getting closer and more intensive, head to the hospital!