Heartburn or what is it?

Jen
I'm 5w1d and ALL day long yesterday at work I was in the worst pain ever and it was very uncomfortable. It is below my belly button and travels up my chest. Could it be my uterus stretching plus heartburn? Geez!! I could barley sleep last night and had to sleep half sitting up. I drank some apple cider vinegar with warm water. That seemed to help a tad bit. Anyone else in so much pain?? And this is not accompanied by bleeding and this is not period type cramping. Also this morning was day one of morning sickness actually throwing up 😕