Could i have a post-wisdom teeth removal infection?

i got four out two weeks ago so the pain's all gone now and such and i've gone back to eating normally. however, today i was checking them with a flashlight and noticed there was bits of food attached to the stiches strings (gross, huh?) so i got some tweezers and removed it but there's still the tiniest bit left in them. i looked this up and apparently that's quite normal and should be okay but i also noticed my left gum is pretty swollen, which is the one that had more food in it. could i have an infection or is just irritated from the food and the cleaning?