A friend of mine with HS is on Remicade and it helped her immensely. I have fistulizing Crohn's and just went through this last week with pain while sitting (again) and had to go into the ER and get surgery. Please reach out to a doctor as soon as possible to see if you have an abscess/another fistula, or also consider going to your local ER since you're prone to this. You may need a seton placed to allow it to drain. Waiting until your colonoscopy may just allow it to get worse in the meantime.
I think you should definitely bring up the idea of going on Remicade soon.