If he is suffering from medical symptoms, you will need to take him to a doctor.
Besides the symptoms, why is it that you think someone has cast a spell on him?
Does he have any "enemies"? Anyone trying to get him?
Casting a spell takes energy, time, practice and effort, it is very unusual for someone to even bother casting a spell on another. Also if the caster believes in any of the "rules" such as the three fold, or karma, then they would rarely choose to risk their own wellbeing to cast on another.
Have you tried all other options before coming to magick, or was this your first jump?
You can find a doctor to 'heel' him or you can use some heeling spells on him.
Another thing, do you think your husband has a problem which he don't want to tell others, try to have a small chat with him.
you shouldn't jump to the mystical conclusion. rule out the logical possibilities. why do you think he's been cast on? if he's lethargic maybe it's a vitamin deficiency, health issue, lack of sleep, or stress. if he seems uninterested in you, again, vitamins, sleep, or stress can cause someone to be 'not in the mood'. always check with a doctor first. if you are concerned, you can cleanse and protect your home and family, that can clear away all build up negative energy which may be effecting your husband.