puppy bitting is getting out of hand

i have a 15 week old pit bull-mastiff mix. (i have another post about potty training advice needed). i’ve had him about 4 weeks and his bitting is getting worse and worse. i don’t mind the light mouthing but he’s now biting to hurt us it seems. nothing is getting him to stop ether. i try to redirect with toys, yelp, walk away and ignore. nothing is working. the more you fight him off the harder he coming back, he has bitten me to tears more times than i can count. it gets especially bad right before bed. he sleeps with us in bed (bad ik but we live in a townhouse and he screams all night. he’s perfect during the day as he’s in it 10-15 hours a day) this is just a cry for help at this point