19 weeks and I think I'm having Braxton hicks!!

Courtney • I'm 25. Happily married. Four children and one on the way!
My stomach gets tight and it's hard to breathe. It doesn't hurt but really uncomfortable. It's been happening off and on the last few days and some cramping! Tonight they are getting so tight I feel like throwing up or I'm having acid reflux. I'm only 19 weeks but this is my fifth child. Anyone know if it is or just something else?