Swelling in cheeks and pain after 2 years of Root canaled tooth

Hi
I had an extraction of my lower molar around 14 years ago and 11 years ago I got a bridge fixed.about 2 years ago I started having some discomfort and doc told me I had infection in my 5 th lower molar which was prepped for the bridge.he took the bridge out did rct on the molar and put a new bridge.since past 6 months I have been having swellings , occasional pain in the gums below the tooth on which rct was done. Probably there is some gap between the bridge and the gums and sometime food particles get lodged.after I floss them out carefully infection goes.3months ago I had a swelling in the gums and the doc ( a new one as I relocated) told me that there is a pocket between the gum and the tooth where food particles are getting lodged . He cleaned the area and gave me antibiotics.it did not heal immediately but went away on it's own after 3 weeks and the gum swelling subsided.
Yesterday in the morning I felt slight uneasiness and I thought some food particle has got stuck again.so I used waterpik and also touched the area and pressed it a little to check how much pain was there.by evening my cheeks were swollen and now in the morning swelling has increased .there is pain but not too much. Incidentally I had visited a dentist only 3 days ago (before this swelling)who took an opt for some other purpose and he told me that there is an infection there but I should wait and watch.
What should I do now?what might have happened?if they plan to do an rct again , they will have to take out the bridge ? If yes,will it be easy or will the tooth crack as it's only a 2 year old bridge?
Please advise
Best regards

[Jerome Tsang, DDS]

Its hard to say.  It depends on whether the infection is due to the root canal or due to a gum disease problem.  They could potentially do the root canal through the crown/bridge and re-fill it but if it cracks or breaks, a new one will need to be made.