Is it safe to eat sushi (raw type) when i have large canker sores at the back of my throat. no way to avoid the food touching the sores and one did a minor bleed but for a very short time.

Sushi: Sushi is raw. So probably not a good idea when you have open sores in mouth.

Better to wait: You are at higher risk of infection if you eat raw sushi while you have an open sore in your mouth. Wait until you are healed before eating it.

Canker sores?: Canker sores do not usually occur at the back of your throat and therefore i question your diagnosis. I would start by seeing your own physician for an accurate diagnosis. Then you can ask all your questions.