This is a common disorder, though people do not talk about it too much. It can cause great pain and very disconcerting itches.
Homeopathic Graphites 30C and Homeopathic Silica 30C, taken together for a day or two, one of each per day, usually does the trick.
For intense burning and itching, you can take Homeopathic Alumina 30C on its own or with the above remedies, but usually it is not needed.
For stabbing pains, like a needle being jabbed into your bottom, use Homeopathic Nitricum Acidum 30C.
If 30C is not available you can try any available strength.