The stringy white stuff is pus/infection. Sometimes the stringy kind (as opposed to the solid kernal type) can be harder to get resolved. If that turns out to be the case and it regenerates, then I have had luck with treating that type with sugardine. See post #8 here for information on that...
I would do as @HeritageFan suggested. I always try to do it non cutting first. This is a good article:
http://www.tillysnest.com/2015/12/non-surgical-bumblefoot-treatment.html/?spref=pi
If you don't get all the gunk out the first time it will regenerate and you will need to do again until it...