Oh I feel for you. I have had them, but my first was my worst when it grew to the size of a large sprout under my arm. I went to the Dr's as I couldn't take the pain and he popped me next door to the nurse who applied some Magnesium Sulphate paste (you can buy it from a chemist) and it took about five days of reapplying with dressings before the massacre appeared on my sheets.
I was due to go back to see her that very morning where she attempted to rid me of all of it. I nearly fainted with the pain.
The best thing was when I went to another Dr at the very beginning of one and he stopped it in it's tracks with a scalpel.
They can be very nasty indeed, depending on the severity. I couldn't drive, couldn't move my arm at all the whole time it was growing.