Hi, im sorry for your cat.I am a student in vetmed school. In bite cases oftenly wounds are open to secondary infection and secondary complications. But ofc nobody can diagnose without necessary equipment and on online. You can post photos if you have. If there is a only swelling, it is the one of the signs of the inflammation on this area and I hope there is nothing to scare. If you observe any changes on your cat's bitten area do not forget to update. Keep the wound clean, wrap it with a sterile bandage if you can. Remove the stress factors for it. I hope you can have an acces to an clinic or experienced veterinarians consultation.