It's still likely the herpes virus, that's the only symptoms my cat gets as well. Get some lysine powder and sprinkle a bit in his food, for an adult 11 lb cat 1000 mg for a week or so is usual, than cut back. But for a tiny kitten I guess 1/4 the amount...like 250 mg(?) just guessing by weight. Order it thru iherb.com brand name Carlson Labs. That's human form, cheaper an that one is safe for cats there are no additives. A jar will last you a year, for under $10
When his eyes swell up and close is there yellow goop sticking them closed??
If so this is Herpes Upper Respiratory Sydrome, and is so common in kittens. Sometimes their mom passes it onto them. My Cat , Meezy< has had herpes and this makes her immune compromised. Look for signs of gum disease (Stomatitis) this sometimes goes hand and hand.
Herpes if very common and it will bring repeated colds, watering eyes, runny nose, and sneezing. It seems to be brought on by excess stress, and will hang around for a few weeks. This is something cats can handle unless there is yellow discharge from eyes or nose, then they will need to see the vet since it has turned from a viral to a bacterial infection which needs antibiotics.
I would take your baby to the vet to make sure this is what is going on, and don't worry if this is Herpes Syndrome. Cats live long and healthy lives , but are susceptible to sickness due to their immune systems being compromised by this virus. Some say L-lysine supplements can keep this at bay. Worth a try