yes, give him a bath in dawn dish soap. Make sure to wet and lather his neck first to get a barrier so the fleas don't run to his face. I just found fleas on Coco yesterday and, like yours it is the end of the frontline dose. I then proceeded to give each of my pets a bath in the dish soap because I figure if one has them, they all do. I'm also going to sprinkle boax on my carpets and let it sit for a while and vacuum.. repeat
I also put a dish of water w/soap in it underneath nightlights to catch any fleas that might be wandering the carpets... got three of them in the one I had put in my kids rooms
I'm probably being a bit neurotic but i'm getting new carpeting in the bedrooms next week and I want to rid the house of any fleas ahead of time. They are a nightmare