HI there... I'm sorry you had to go through this you are so young. As everyone here is saying... patience. You will heal. It just takes a bit of time... now physical healing takes approx 6-8 weeks. But by then they will likely have started you onto rads. It does often make fizzy drinks painful (frankly I'm 4 years out and I still don't drink pop (mostly because my mouth now has a built in chemical shit alarm and pop tastes positively HEINOUS.) So do sugary fruit juices - particularly sugary ones. I drink a lot of green tea, and water with lemon. If I want a bit of fizz I throw in lemon juice/lemonade with plain fizzy water which tastes okay (I can control the fizz by adding more regular water so it doesn't burn so badly) but normally I'll do the water and lemon thing.
As someone says everyone responds differently. I don't do spicy, super acidic, or fake foods (processed) but everything else is good.

Once you get the sip working it will be easier to eat. I used to put a bit in my mouth and swallow my food with water. I still do with some of the more difficult stuff (bulky things)

Rads will not be fun. But you're young and strong and you will get through it.

Hugs