Extreme selective eater

Patient: HI PLEASE HELP ME!!I have been suffering with selective eating disorder for many years but for the last two years or so it has taken on a whole new level. I am currently in university studying biochemistry. I ONLY eat bread, everyday all day, I am at a fairly normal weight but I can feel my body breaking down, I cant concentrate, my hair is falling out, heart palpitations etc. Can I ask to have a PEG or nasogastric tube inserted for this, just so my body can recover?( I have tried eating other foods countless times but I literally CAN’T)

Symptoms: Hair falling out, EXTREME fatigue, trouble concentrating, heart palpitations….