Lump in throat feeling?

Before the feeling I had heartburn like everyday for a few weeks now I have this lump flem feeling on my gag reflex it goes away and comes back and sometimes a little not of clear flem with a little blood in it comes up I am 17 years old and I used to be a half a pack a day smoker but this feeling has cause major anxiety about cancer that I only have acouple a day I had a neck X-ray and they said it was normal please help !!! Ive had this feeling for over a month