My mother is a 49 year old diagnosed with schizophrenia and bipolar disorder in her early 20s. She also has OCD and was diagnosed with rheumatoid arthritis when she was 37 years old. I'm not sure what form of schizophrenia she has (I just found out about it 2 weeks ago) but she apparently would hear voices. She's never had visual hallucinations, is not paranoid, but can be very socially withdrawn. Her bipolar disorder was pretty well controlled as far as I know. It seemed rare that she would have any serious exacerbations that I know of. Anyway--
About a month ago both her and my father had bad head colds. My dad actually lost his sense of smell for about two weeks (which I think may be significant because whatever he had may have involved a cranial nerve... possibly. I don't know.) and my mother developed some cognitive issues at this time.She started struggling to find words and couldn't seem to associate words with appropriate objects (for example: dad would ask her to give him his car keys and she would hand him the phone). She started having trouble with memory, not remembering things said in conversations ten minutes early. I noticed when she would ask me how work was three times in a row. She won't eat unless my dad makes her... which is a problem because he is at work all day so she won't eat. Then she will lie and say that she ate when she did not. Her behavior has become increasingly bizarre-- like after dinner one night she started cleaning up and took all of the garbage and wrapped it up in paper towels and left it on the seat. She is taking multiple showers a day and changes her clothes 3-4 times a day. Just today my father came home from work and found some potatoes in ziplock bags in the oven. Luckily she didn't turn the oven on. My father said this is unlike any exacerbation of her illness that she's ever had so he took her to her primary care doctor. They ordered bloodwork and sent her to a neurologist. Her bloodwork results were a decreased TSH, increased T3 and T4, hypercalcemia, hyperkalemia, and an elevated WBC. The neurologist prescribed an MRI of the brain and an EEG *both of which have been pending insurance approval for two weeks now* and referred her to an endocrinologist. He believes that her problem has to do with her thyroid and the calcium levels. She saw the endocrinologist, who did more extensive endocrine studies. Her hypercalcemia and hyperkalemia improved, and he said her thyroid levels were not significant enough to cause such drastic neurologic changes. He referred her back to the neurologist saying it is not an endocrine issue.
She is currently taking Lithium, Haldol, Lorazepam, Cogentin, Methotrexate *RA*, Naproxen, folic acid, vitamin d, and a multivitamin. I think that's everything but I'm not positive.
Her older sister was recently diagnosed with MS but did not experience any cognitive changes. She had a brain scan done three weeks ago, however, that shows lesions on her brain.

So the ultimate question is, based on the above information, what could be happening to my mother? I'm scared we won't get her back and I don't know what to do. I'm thinking that the cold she had may have caused something or maybe let another underlying disease process come out but I really don't know. This is all very unlike her and I have no clue what could be going on. Any suggestions or help would be greatly appreciated.