What Could Be The Possibilities From My Problem Of Sleeping

What could be the possibilities from my problem of sleeping too much,10 hours a night and then waking more tired than when I went to bed? and I stay sleepy and wobble headed all day. I have no head aches but my head does stay hot most of the time. I`m 69 years old and I have had throat cancer 12 years ago and I lost my voice box. Anyway,this sleepy problem has been going on about 6 to 8 months.