At week 14, I don't think it's phlegm. You must be throwing up acid reflux that causes pain especially during an empty stomach. It usually is yellow or green and very bitter. I threw that alot when I was in 1st tri. Hang in there ok! You'll gradually get better. Try not to eat anything spicy that may trigger the nausea. I also avoid eating at night although my stomach is growling in hunger. I don't want to have trouble sleeping cos heartburn is very painful
Vomiting is normal during pregnancy, but if you feel that is not normal than morning sickness . it is better to contact your doctor.