My experience may or may not be of use to you.
I used to suffer from boils (on my back), but then completely eliminated them (after a lot of trial and error) by
1/ giving up dairy products entirely, and
2/ never using soap on my skin, (just pure water, apart from hand-washing, that is).
Going non-dairy is not that easy to begin with, but has other health benefits associated with it.
The second measure is counter-intuitive, but we are a product of evolution, and our ancestors did not have harsh soap products marketed at them. As a bonus, the bath is much easier to clean, without all that soapy scum stuck to the sides.
Steve