The peroxide bubbled into your throat? With the forehead down that is difficult to do because the throat would be higher than the sinuses and nasal passages. That's one reason that I do it upside down, to avoid swallowing the mixture. Another reason is that it enables the anti-infective mixture to flood the nasal passages and the turbinates, and to seep into the sinus cavities. I also gargle with peroxide. It is great stuff!
The bubbles/foam is pure oxygen. Peroxide foams when it meets with damaged nasal passages, damaged turbinates or damaged sinus membranes, or blood. Peroxide will also kill many different types of infectious bacteria, fungus and virus, and the pure oxygen foam will also kill many types of germs.
I did about 40 "upside down sinus floodings" during a two year period, before I felt that my sinuses were healed, and then I posted about it on the Internet.
I also have made major changes to my lifestyle to avoid allergens and pollutants, I have had allergy shots and acupuncture treatments.
I had sinus surgery, in my right sinuses, for a cyst and a deviated septum, about 25 years ago. The surgery produced scars in my right sinus, and my sinus problems and infections would always start in the right sinus. I understand that there are ways to do the surgery today that doesn't leave scarring. You should check with your ENT about avoiding scarring.
Getting rid of sinus disease is difficult, complex and frustrating. Best of luck finding a cure for yours.