For 2 years i've had thirst and feel dehydrated but now it's worse and more frequent. sodium is 143, potassium is 4.1. diabetes and addinson's were ruled out. have a dry mouth, sometimes pee less which is concentrated with smell. what could it be?

By the sodium level your body fluid is on the low side but not consistent with dehydration. If you drink less and urine is concentrated and smelled stronger you do not have diabetes insipidus. I wonder if your symptoms are due to dry mouth due to poor saliva excretion. Have you ever worked up for condition such as Sjogren's syndrome. This condition causes dry mouth but not true thirsty.

Dry mouth can be caused by sleeping with mouth open, dehydration etc. Make sure the humidity in the house is OK, drink plenty of water and get a Urinalysis. If symptoms persist see the MD again