Problem with my dad, help?

my dad never washes his coats and sweaters, and they smell horrible. he smells like a homeless man when he wears something like that. i also think his hygiene has tanked, like he showers twice a week, and when he takes his shoes off his feet smell strong at times. sometimes when i go near him there's a bit of a smell from him, if he hasn't showered lately. he also has bad dandruff and his shoulders are covered in it, it's really nasty.

i've been telling him every time i see him for the last two years or so. i didn't see him often for a couple years, and before when i lived with him it wasn't like this. he would shower every single day, he would never smell bad, his coats etc would never smell bad, he did have dandruff but less and he would really care about it and deliberately make sure it didn't coat on his shoulders. it might have to do with divorcing my mom (he still wears the wedding ring, four years later almost) and living alone. he tells me he doesn't care at all about his dandruff or his looks (besides his weight, he goes on diets but is about normal/slightly pudgy) and he says he can't smell what i'm talking about.

it really bothers me, especially when i'm with him in public. i feel very uncomfortable being associated with someone that smells like a homeless man with horrible dandruff. especially the smell. many older men have that dandruff problem and for some reason don't care, but the smell is just, horrible. i feel uncomfortable being in the car with him at times or being in close proximity.

what can i do to get him to stop stinking and to go see a dermatologist?

Problem with my dad, help?
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