HELP!!! I think my kitten has a catnip problem, what should I do?

Ever since he tried catnip last weekend, he hasnt been the same. He already used up his first bottle and now he has another one some how. I think he is stealing because I checked my wallet today and 20 bucks was missing, I confronted about but all he did was meow and turn his head to the side. Can someone help me and give me answers on how to get my old kitten back. He is only 6 months old and I dont want him to end like those cats in the alleys. =(