I started vomiting this morning and it was a bitter taste that was yellow.what does that mean?

Biliary emesis: Bile is typically a golden yellow to green color. It mixes with food to help digest dietary fats. When bile backs up into the stomach, it may appear in your vomitus. When persistent, it can lead to alkaline reflux and stomach irritation. Lots of common things can cause bilary emesis, but if persistent, worsening, or associated with pain, tenderness, weight loss, blood then please have it evaluated

Probably bile: If you have no food in the stomach when you vomit, what comes are gall bladder secretions that are there to help digest fatty foods. It is not dangerous to have this happen, but you may want to know the cause of the vomiting - that could be important to deal with. Hope you feel better soon.