I don't know what it is for you but what you described is how I feel if I had between 8-10 hours of sleep,which isn't very often.And it seems to stay that way pretty much all day,it's like I get too much sleep or something and can't wake up.

It might be a good idea for you to call your doctor or pharmacist and ask if combining the meds could have caused that to happen,just to be safe.