what happend to Danny mills

No, it's not the same person. They do look quite a bit alike, but they're not the same. If you look closely, their facial features are different. Gator is not Danny Mills but Michael Potter. According to IMDb, they were both in only one of Waters' "full-length" films, though Mills was in a couple of films on Waters (and his characters) by others, and Potter was in an episode of the TV series The pretender in 2000. I believe that on Waters' commentary on FT, he says Potter "was straight, but he had a sense of humor about the role."

Actually, it just occurred to me that Michael Potter is probably a fairly common name, so I wonder if IMDb could be wrong that the person on the TV episode is the same. I don't think I saw it, so I can't make a judgment about whether it was an older Michael Potter. It would be odd if a person did just those two things, so widely separated and unrelated. You'd think he would've had more of a TV career in between if they were the same person.

"Extremism in the pursuit of moderation is no vice."

Nope. I haven't got it to hand right now but John talks about Danny in 'Shock Value'. I know that in the introduction to his collection of the screenplays of 'Pink Flamingoes', 'Desperate Living' and the (never made) 'Flamingoes Forever', John says that Danny was involved with the biggest LSD ring in the country! If you've the US DVD's then John talks about what happened to them both. I don't think either of them acted again which is a shame. Michael Potter was kind of cute and Danny Mills is a complete hero for the 'Blow-Job' scene, a straight guy who had no problem with it, could see the comedic value etc...a star. Hope this was some help.