anal itch

I've had an anal itch for over four years now. Anti-itch cream helps to lessen or stop the itching. But otherwise the itching doesn't go away
I've seen a doctor about this problem, but he seemed to think that the itching would stop (permanently) after I used a prescription medecine, and sure enough, the itching came right back as soon as I stopped using the prescription cream. I also have a watery like discharge that comes from the same place every once in a while.
It's not a huge problem because I can just buy the inexpensive over the counter anti itch cream to relieve my itching, so most of the problem goes unoticed (except when i wake up in the morning, or when the anti itch cream comes off during the day). But I'd still like to know the underlying cause to my condition. So, if anyone can tell me possible causes, their insight would be greatly appriciated. I'm only 17, and I'm kind of ignorant about these medical issues. I figured that this was some sort of yeast infection, but would a yeast infection last this long?

Do you have back or nerve damage? Also Diabetes can cause it.My ex hubby has the same they are now testing him for diabetes,and was told shingles spinal stenosis, and so on can cause it.He has both,,goodluck

ive been having the same problem for almost 3 years now and i don't know what it is im a virgian so it cant be that and the last time i went to see the doctor he wanted to open a file like it was nothing he had ever seen before it was wierd i thought it was some part of puberty or something and i thought it would go away. i really just dont under stand it tend to happen when im nervios or around groups of people and i feel this insane burning around my but hole. if you can help.