Can Keflex 500mg Causes Swelling In Gums?

the gums on the right side of my mouth are swollen and have been since last night. I m crying in pain. I can t eat and now my throat hurts when I swallow. I m taking keflex 500mg twice a day to prevent an infection for stitches I got in my foot. I started taking it last night is this related? Should I go to to the er?