ASD 8 yr old, being incontinent?

My son is 8 1/2 yrs old and was diagnosed with ASD along with RO mood disorder NOS/ ADHD about a year and a half ago.  My son has never been night time continent.  After consulting a few medical doctors and his psychiatrist, I was informed that was not very odd for some 8 yrs olds and even more common among ASD children.   As time has gone on, he has now become fecal incontinent during the day.  He will only use the bathroom to urinate.  It started out about a year ago with him holding it in and having to coax him to go and help him wipe with a struggle.  Now he just constantly goes in his pants and now is in complete denial about it, even when I show him the messy underpants.  He will act as if he has no clue how that got there and will become very defensive on the subject.  His new psychiatrist also recently changed his RO mood disorder NOS to strait up depression and medicated for it. What is going on?  I'm at a loss.   This happens all the time and everywhere.  School, home, visitation with Dad, in the community, etc...  I cant understand how a kid went from RO mood disorder NOS to depressed and medicated and from fecal continent to incontinent in a year and a half.  Any ideas?

[Lireal]

What triggers his incontinence?