My havense 9 year old has a fear of thunder. I have medicated him for this three times in the last month. But now with no medication for weeks and no thunder, he wakes me up several times a night clawing at the floor, though not really in much of a panic. I tell him "no" and he stops for a minute and then starts up again. What can I do? He is a very sweet dog with no other behavior problems whatsoever.