tongue cancer?

hi everyone,

I am 16 years old, i smoke weed 2-3 times a week, i did those pouches that are like chew tobacco that you put by your gums and a month ago i did a  pouch before i went to sleep and woke up with haorse throat and my throat burned like crazy. It was like this for another week and i stuck out my tongue and noticed like 5-6 bumps on the back of my tongue and white coating all around that smells like horse ****. I lost about 7 pounds in a month maybe more and  i went to a ENT and he said it was nothing to worry about but now i noticed all the way back in my throat a yellow line that goes down. I am really scared i have tongue cancer or some kind of cancer from reading all these websites. I dont know what to do, i am depressed a lot now and started to do bad in school . Any advise is welcome , thanks