Hi ma'am.
If it's associated with pain, then that signals towards an infection, which should be treated with antibiotics, which you've already given.
Hopefully now it's not painful, and that means mostly the infection is resolved, and its just fluid inside the sinus that's getting drained out. And you don't need to worry about it.
The final treatment is surgery, yes.
It's not urgent though.
Next Steps
Get it excised surgically whenever you can. look out for pain/redness/swelling around sinus, if any of these appear- consult a doctor.
Health Tips
You can keep applying some local antibiotic ointment, to prevent infection for now.