Finding a diagnosis

I recently went to a Nephrologist and am going to do a water deprivation test to try and diagnose me.She thinks I may have Diabetes Insipidus. Nephrogenic over Central is suspected, since I have been on LIthium. I'm really worn out and am down. I'm also having trouble with constipation because of all the fluid intake and output. I know online it says this is more of a rare disease, but I'm hoping that someone will notice this and may be able to relate. I'm also concerned that if this is the case, I will have to reduce or stop taking Lithium all together...and medication changes are really hard on me. Trying not to worry, just depressed.