We have an 8 week old that has a minor case of fleas as we got him at roughly six weeks. I would like advice on a safe flea treatment as I know how sensitive they are and some flea treatments are very harmful. I am anxious to help him, and us frankly, but want to be cautious. Any advice is super appreciated. He is our 7th rescue and all others were raised from pinkies or weeks old and thus had no fleas.