Potty Training still...

I am so frustrated, everything I knew, have read, and thought about potty training has gone out the window with Tyson. This kid will not wake up for anything to go potty, and to make things worse, now he has a horrible habit of waiting until he pees a little and then goes potty.  He will not go if we ask him too.  He will not go for treats or anything else.  We have tried rewarding him with parties, toys, stickers, candy, you name it we have tried.  We have tried ignoring it hoping it would cure itself.  We have tried waking him up in the night.  We have tried pullups, going back to diapers at night, etc...but nothing.  I am so tired of washing bedding, blankets, chairs/couches(where he falls asleep), underwear, pants, giving millions of baths and seeing his poor body be scared by scary looking rashes because it is burning his skin at times.  I feel so bad for him when I look at his rashes, but I am at my wits end to know what to do.  Anybody out there have any suggestions that maybe we haven't tried, I am desperate.  And I am beginning to think he will never learn and that it would be easier to have him in diapers...but maybe there is something wrong with his little system, maybe we should have him checked out...I don't know...all I know is I think Sarah will be potty trained before he will...not that we have even attempted that yet.