I Have A Question Concerning My Throat. For About Over

I have a question concerning my throat. For about over a year I will have troubles swallowing and have to eat really slow. And it always feels like there is something in my throat. For the past day it has felt like there is this sharp pain on the right side of my throat just a little bit underneath my chin. Im worried it could be throat cancer. I also want to note that I did have acid reflux really bad but I have been taking medication every day to help. But I use to use tobacco a lot. And every night when I try to fall asleep as soon as I am about to fall asleep I suddenly feel like I can't breathe at all hardly and I have to sit up to catch my breath. I have no idea what it is. I went to a throat doctor a year ago and he said it was mucus in the back of my throat that was making me feel like I couldn't swallow. But it's gotten to the point to wear it freaks me out. Some days I can eat perfectly now and some days I can't hardly eat at all. I constantly feel like I can't breathe and it's extremely hard for me to fall asleep. I just want to know what to do. Im really concerned it could be cancer or something. And im only 21.