I had a very itchy bottom for about 1 year, but do not suffer now. It started off when I had some mild constipation, which caused a very small hemorroid to become irritated. This caused mild itchyness around the anus area, but nothing serious. At first I scratched to get rid of the itch and washed more thoroughly with soap because I thought the itch was due to cleanliness. This made the condition much worse, which caused me to wash it more thoroughly with harsher soaps, which made it even worse and so on.
The doctor prescribed some drugs to rub on my anus, and some other drugs to insert up my anus, but these made absolutely no difference. After experimenting with lots of things I have found that the following rules, when followed strictly for (in my case) 5 months, may resolve the issue:
[1] Dont scratch it. Also when you go to the toilet dont use harsh paper, and rub as gently as possible to clean yourself after you are done.
[2] Clean the area daily, with WARM WATER. NEVER USE SOAP. After you are done, dry the area fully with a hair dryer. Do not put any chemical of any kind on the skin. Although these may relieve symptoms they are unlikely to provide a cure (in my opinion). Better I think to let nature run its course.
[3] The itchyness is often a result of another problem (In my case mild hemorroids that I did not even know were there). Therefore it is a good idea to try to maintain a healthy gut and keep the stools soft, bulky and easy to pass. Therefore I recommend that you change diet if necessary towards consuming much more healthy high fibre foods such as fruit and veg, brown bread, brown pasta and brown rice, and increase you fluid intake. Changes in lifestyle that reduce the stress in your life and make you healthier, for example exercise, can also only be beneficial. I found when I reduced stress by working less, exercising more and eating healthy that not only did my symptoms reduce, but I also cared less and thought less about them.
Recovery in my case was slow and frustrating and at times I wondered whether what I was doing was working at all. But eventually you may turn the corner with this problem if you follow the above recommendations. In my case the itchyness would go for a few days, then would return with a vengeance. After a while, the relapses would become less severe and less frequent. Now I hardly ever feel an itch down there. The skin feels healthy.