That use to happen to me. Brush your teeth in the morning before eating you will gag it will be uncomfy but it will keep you from having to rebrush then use mouth wash during the day. And at night don't brush your teeth until 1-2 hours after you eat and do it quickly then use mouth wash.
Someone told me to try kids toothpaste lol
Mouth wash?? Maybe a few times a day will help until you can brush again. I'm sure its just a phase. :(