I Am Having A Problem With A Change Of The

I am having a problem with a change of the manufacturer of a medication I take. I take Ondansetron for my MS. I was taking the brand made by Apotex. They switched the brand to Cobalt. I have done some research to find any differences because it is not working as well.
By Apotex it is Ondansetron Hydrochloride and by Cobalt it is Ondansetron Hydrochloride Dihydrate. Can you tell me what the Dihydrate is? Is it possible it they would work differently for me?