Hello, My 22 year old son has been complaining of difficulty swallowing over the last few days. There is a white coating at the back of his tongue and directly behind it a line of red dots going horizontally across the very back of his tongue. I had to use a flashlight to see it. He says he can taste blood. He wonders if it might be oral ulcers or maybe something else, and is not sure if this is serious and requires a doctor visit. What would you suggest? Thank you.