The problems I had with anal rash in the past were caused by not getting all the fecal material removed from the anal area after I had a bowel movement.
What I have found is that cleanliness is the best treatment for anal rash problems. This means much more than just doing a good job of cleaning the anal area when taking a shower.
1. First, many people, including myself, have quite a bit of hair growing around the anal area. It is almost impossible to clean the fecal debri left after a bowel movement out of this hair. The solution is to get someone (my wife does it for me) to trim the hair after a shower. My wife uses electric hair trimmers and is, of course, very careful. You will get some slight itchyness for a few days following this as the trimmed hair starts to grow back in, but this quickly goes away.
2. When you have a bowel movement, first wipe yourself with dry toilet paper to remove most of the fecal debri. Then clean yourself well by using folded toilet paper (at least 4 layers of double ply) moistened with tap water. Wipe and re-wipe until there is no brown material left on the paper. Then dry yourself. - NOTE! - DEPENDING ON HOW MUCH WIPING YOU DO, YOU MAY HAVE TO FLUSH THE TOILET 0NE OR MORE TIMES DURING THE PROCESS SO YOU DON'T PLUG IT UP.
3. On trips or at work where tap water to moisten the toilet paper may not be easily available, I use the moist wipes you can now buy in most grocery stores to do the cleaning job. I do not use these all the time because, at least in my case, they sometimes cause there own rash problems. For me, using them once a day at work works out OK.
So, for me, trimming the anal hair and keeping clean work much much better than any cream or treatment the doctor has recommended.
I think that the cause of these problems are from the food we are eating. I find mine gets bad from dairy that is not organic and from anything with artificial sweeteners. I am thinking that there are a lot of additives that are causing these problems which are getting more pronounced all of the time.I am going to do a couple of liver cleanses, probably one every three months for a while. And I will stop eating things that are causing the problem to be more pronounced.