Hello and Thank You for contacting JustAnswerI am sorry to hear your baby is having trouble.
Its possible what you are seeing is a embedded larva of the Cuterebra fly.
Cats can acquire cuterebra larva after curious investigations of a rodent or rabbit or their dens when outside
Most cuterebra larvae are found on the head and neck of cats. Sometimes, the larvae migrate abnormally and end up traveling through the brain. This can result in fatal brain and nervous system abnormalities, such as seizures.
If this is the case attempting to remove this can cause serious side effects, It is highly recommended to have this removed at your vets office. If the larval body is ruptured during the extraction process, the cat can develop serious complications such as severe allergic reactions For this reason, the breathing hole is typically enlarged and the larva are safely removed with a forceps or hemostat, and the area is flushed and cleaned with disinfectant. Antibiotics may also be needed
You can read more about this problem here
This could also be an abscess caused by a scratch or bite of another cat.
Read more here
I would suggest having him seen as soon as possible by your vet.
I hope this has been helpful,please reply back if you have additional questions or concerns