Unexplained white and yellow mucus in stools for months

Back in October, I started noticing "white stuff" in my stools, sometimes with a little yellow if I looked closer. I had never experienced this and at first I thought I had parasites because of the shape this white stuff would sometimes take on and the way it would sometimes be hanging off of the stool. After it happened the first time, it continuously happened. Sometimes I would see a lot and sometimes just a little and a few times, none at all. I noticed that if I was a little constipated beforehand, I would see even more of it and I could expect to see it every time.

I made several doctor's appointments and I had a stool sample and culture done; both came back negative. A few weeks ago my doctor decided to refer me to a specialist since he couldn't figure out what could be causing this, especially because it had never happened before and is now continuously happening since it began. I was referred to Mayo since I only live 40 minutes away but my appointment was denied. I'm on a medication called Accutane and I have about a month left of taking it so I thought I would wait until after I had finished to see if that was perhaps causing it before I made an appointment for another referral. However, I've noticed it seems to be getting worse. Now, every time I pass a stool, I see this white stuff that I have now decided must be mucus. I see patches of both yellow and white now, although white is still the primary color I see. The amount I see still varies from time to time but it's always there.

As far as I know, I don't have any other symptoms. I have always gotten a little constipated from time to time and my doctor said that was nothing to worry about. I do get abdominal pain at times but I've always had that and it's nothing too severe, and something that has gone on far before this started happening. I have had anal itching, which also made me think I had parasites, but I'm wondering now if something in my stools is causing that itch? That could be nothing as well though.

If this doesn't stop after my medication, I am definitely going back in for another referral but, in the mean time, does anyone know what could be causing this mucus? :-(