I've been experiencing mornings where I feel like I have to vomit and when I do, my gag reflex kicks in and I throw up a lot of mucus. Why?

Nausea in the mornin. There are several causes for nausea in the morning that range from hormonal changes in the body, to medications, to stomach/bowel irritation from food sources and infections, to ulcers and beyond. I would try to find out the cause of the nausea by seeing a GI specialist. The gag reflex is a normal reaction when nauseated and mucus may be from the stomach or the throat. Needs to be evaluated more.
Morning nausea. First make sure you're not pregant. If you're not, the most common cause of morning nausea is excess stomach build-up. Try before bedtime doses of otc Pepcid (famotidine) or Prilosec to see if it helps. If not, consider other causes like stress (try to relax more), alcohol (try to drink less), other medications.