My 3 week old pit bull have fleas and he also don't like the milk re placer what should i do ?

I have a 3week old pit bull and am bottle feeding him with some milk re placer and he don't want the bottle what should i do ??? He also have a lot of fleas , hes to little for me to bathe him i don't know what to do he so tinny that i don't want him to die on me !!! I need help .