I go for quarterly periodontal cleanings. yesterday, i flossed an upper tooth's gum area pushing into the gum tissue. i can feel some swelling; no pain or blood. would an antibiotic help if no infection?

Antibiotics have in general a mild anti inflammatory effect aside from their effect on bacteria. If no infection, their use is not recommended as it can result in side effects and more importantly creating the premises for bacterial resistance whenever needed in the future.

No. Antibiotics are used to kill the bacteria that cause an infection. If you have no infection there is no need for antibiotic. Your discomfort may be from inappropriate use noffloss causing bruised or cut gums. You have a Periodontist. Avail yourself if his/her services. Give the office call. In the meantime try salt water rinses.