my puppy’s biting is getting worse and i have no idea how to stop it.

i have a 20 week old golden retriever male puppy that was progressing with biting me less (bites more/harder when overstimulated or sleepy) but right now he’s been biting me super hard every time i touch him or not play with him. i got nail clippers/file today and slowly desensitized him by rewarding when he doesn’t react, once i got the file on and tried it on his nails he became more aggressive the whole day, i took him to the groomers two times before and i fear this has caused this bc of how traumatic it must’ve been for him? idk, but touching his paw became harder. he’s obviously losing teeth and getting new ones but the bite inhibition is absolutely not working and my hands have had tiny bruises from his bites, bleeding from scratches. i’m so worried that he has some sort of aggression and it’d get worse as he grows up. i don’t wanna use the last case solution like a E collar or something. i’ve tried everything from redirecting to toys to leaving the room. PLEASE HELP.