Spouse with chronic illness - anyone else?

Hi ladies! My husband has been dealing with chronic & constant headaches, along with other concerning symptoms, for the past couple of months (no diagnosis yet, but that's a whole different story). In that time, he has gone through quite a dramatic change. He's moody and snippy, exhausted all of the time, and never up for sex - nothing like how I'm used to him being. Obviously, this is not really his fault, he's sick!! The meds he's been prescribed aren't really helping the situation either. However, I feel like I've completely lost my husband, like I've been demoted to roommate/maid. And I feel absolutely awful for feeling that way. Have any of you ladies dealt with this kind of situation? How did you cope? I'm so lost on all of this, hubby has always been the "rock" in our relationship and I'm not dealing with this very well on my own.