Hello~I highly suggest you see your physician, it sounds like diabetes tome, you should have a 3 or 6 hour glucose tolerance run plus an A1c, these will be very good indicators of what is going on with your sugar levels. Please do this as soon as possible, your symptoms don't sound good, they need to be addressed.
I have a soreness around the anial area that is painful when cleaning myself. This has persisted for 6 months or more. I use some "triple antibact. Cream" which helps some, but continues to be present or recurring. It seems to be more prevalent after I have used a "Laxative". There is no itch associated with the condition.
Rheumatic Fever can cause scarring on the brain, heart, kidneys and other organs but even if that werent the case you need to see a physician asap as these symptoms sounds very serious to me. Even if its diabetes insipidus you need to be treated by a physician