I had some axio labs gear a while back that gave me really bad abscesses like yours. I got about 4 abscesses in a row, all different sites, before I decided there must be an issue with the gear and threw it out. Incidentally they had been busted right around that time and the word was that QC had slipped toward the end.
Not saying your gear is bad, cause like I said I've also had the exact quad/knee traveling abscess like yours and the gear wasn't the issue.
Just throwing the axio story out there cause it is something to keep in mind when dealing with an abscess.