How To Cure Severe Tiredness,sleepiness And Diagnosed With Multiple Sclerosis?

I have MS and I do is sleep. I cannot stay awake more than 3-4 hours at a time. I'm emotional, tired of being tired and it's taking over my life. I'm miserable. I do still work, although its a struggle to stay awake at my desk. When I get home, I give myself a shot and go to bed. I'm sleeping 12 hours and when I wake up, it feels like I never slept. Still exhausted. Please help or suggest something to do