How do I sort out my nose piercing problem?

by Holly
(Warwickshire, UK)

I had my nose pierced on the 23rd December 2011, I've been cleaning it constantly and it has been fine up until recently.
My skin has formed a red raw bump right on the piercing which has been leaking a clear/white substance daily, when it first appeared I went straight to a piercer and he told me it was slightly infected. But it has got much worse over the last week. The head of the stud keeps sticking to my 'bump/skin'. I've been putting tea tree oil given to me when I first got it pierced and have soaked my nose in warm salt/rock water a few times.
I'm really reluctant to take the stud out and let it heal as it was quite expensive and I don't really want to re pierce scar tissue.
Does anyone have any suggestions on what to do?

Here are a couple of pictures: http://imgur.com/a/xY8HC