I have done my research and it doesn't sound too much like either of them. There would be visible signs of FeL in my cats because I have cats that are 9 mo. who had this eye/repirtory infection. I think it is this:
This is a fairly common disease too, but luckily it's much easier to treat (treated with antibiotics). Symptoms include runny or weepy eyes, wetness around the nostrils, and sneezing. Cats rarely sneeze, unless there's a lot of dust in the air, but if you hear your cat sneezing and there's seemingly no reason, call your vet for an appointment. You may also notice the presence of a white eyelid in the corner of his/her eyes. The cat may also feel warmer than usual (indicating a fever), and s/he may refuse food and water and lie around listlessly. It's imperative that they do not get dehydrated! In bad cases, you can buy a bottle of Pedialite in the infant section of the grocery store (get the unflavoured kind), and mix a little in with the cat's water bowl. You could also take a needleless syringe and squirt some into their mouth; two or three syringe-fulls every couple of hours should be sufficient. But do this only with the vet's ok; if your cat is on other medication it could be harmful or ineffective. This is contagious, so keep other cats away and wash your hands after handling him/her.
Whatever it is, I am taking one of my female cats whose kittens have had this problem more than the others tomorrow to have her tested.