How should I fight dehydration with Diabetes insipidus and…?

I am newly diagnosed with DI with in the past month, and the doctors are still playing with my meds. right now there giving me too little, I've been sick for the past 3 weeks with what I assumed to be the virus that is getting everybody sick. I finally went to the doctor last saturday and they said I have walking pnueomia. I have been staying home and taking the meds but I'm really scared I'm dehydrated. anything I drink goes straight through me and my blood presure is low because everytime I stand I feel dizzy for the first few seconds and then get sick to my stomach if I stand to long. I don't know what i should do? If I can how do I get and stay hydrated while I get better?