This is the second month that Samson has been on frotline and it isn't killing fleas. He is always itchy and we are always brushing fleas out. We just gave him a dose of it a few days ago to make sure the first time we just didn't get it on good. This time we were very careful putting it on and it still isn't working. I have heard about pill form but can I give another flea preventitive while on frontline? If not what can I do right now to help manage the fleas?