Flea bites how to stop them hurting?

Flea bites. First wash the bite with cool water & mild soap (hot water intensifies the itch); pat dry; don't scratch; apply tiny dab of Hydrocortisone cream or some tea tree oil or witch hazel or aloe vera gel or neem oil to calm the itching. For more persistent itching, use otc antihistamine like Benadryl (diphenhydramine) or zyrtec. Of course, controlling the source of the fleas is critical, too.
Anti-itch medication. Flea bites generally should not hurt. They usually itch to the point of heavy scratching causing skin breakdown which becomes an open sore. This is the point where pain is usually present. If you use a realy good itch reliever like Eurax (crotamiton) cream otc, it may prevent you from breaking skin surface and no pain. Breaking the skin surface by scratching is a potential skin infection and much pain.
Various things work. I would suggest that you stay clean, but don't wash or scrub the bites too much. Sarna lotion and any treatment for poison ivy, including Hydrocortisone cream 1% or caladryl lotion may be soothing. For itching use a non sedating antihistamine like Loratadine or fexofenadine, both available over the counter. At night, diphenhidramine (benedryl) works well for the itch; don't use it during the day.