Hi,
i know you posted your message a little while ago but I thought I would reply.
Does the itchiness get worse at night? Does the skin bleed if you scratch it too much and are the lumps painful? I think they call it (no joke) itchy anus syndrome and it's very common although there is no cure. A few pointers I could give you are:
* no harsh chemicals to clean the itchy spot like soap - just warm water.
* after going to the toilet try not to wipe to harshly but 'pat' and if you can use moist wipes rather than dry toilet paper that often helps.
* you buy some cream over the counter (i know that you can in australia anyaway) that is a hydrocortisone cream which relieves the itch and sting.
* try not to scratch - although it does drive you crazy if you don't.
* I know all this because I suffer the same thing - and there is not much anyone can do about it - it's just a pain in the butt - pardon the pun!
Hope this helps