Have a consistent slightly itchy and uncomfortable throat. Doesn't feel quite like a sore throat and been on and off for a year and a half. Wht to do?

Allergy. Given the duration i would see my md and have them check for allergies. It has been a terrible allergy season the last few years and people who normally are not affected have been. If your md looks at your throat and it looks like prime beef it is most likely and allergy so please see your md.