Lower abdominal tightness during 19 weeks?

Gabriela • First time mom. 23. Due 06.26.17
I've been getting these weired lower abdominal tightness/wave type feeling that  goes away in minutes. It doesn't hurt as much as it feels weired. I am not sure if it might be the baby, because its in the same location where the doctor puts the doppler for the heartbeat. 
Is this Braxton hicks or is this just the baby pushing my organs?