Can Lithium Or Depakote Help In Treating Manic Episodes?

my husband of 32 years has had what appears to be a manic episode brought on, I believe, by extreme stress and frustration at work. He has some symptoms of mania but he is not bipolar and is 58 years old. His behavior is completely unusual and he is not himself. One of my concerns is a physical abnormality such as a brain tumor or blood clot. He had a CT scan at the ER because I was at my wits end, I took him because his doctor was not available that day. CT scan showed nothing but should I pursue an MRI? It has been a month since the first symptoms started. His primary doctor put him on Lexapro for anxiety but we saw a psychiatrist who said Lexapro may not be the best thing, it may cause more energy and that is not what my husband needs, he is going non-stop and is not sleeping very many hours. The psychiatrist recommends maybe Lithium or Depakote and is in the process of sending his report to the primary care doctor. What else can I do? Or what other type of doctor can I see? Should I see a neurologist?