Young cat with URI and mouth sores- antibiotics help, then URI comes back!

Hello, new to thread so bear with me lol. I adopted a cat last fall (2012) and he's a little less than a year old. He was sick when I first got him and was put on clavamox. He ran out, and symptoms never fully went away. So he went back on the clavamox. After that also failed, the vet prescribed me doxycycline. That seemed to have knocked it out of his system for about 2 months. But then the stuffy nose, and wheezing came back, but this time he developed mouth sores! they stayed a week before going away. that was the only time ive seen them. The URI has happened at least once a month and I've stopped putting him on antibiotics bc it doesn't seem to help. Vet said that he's just a "sick cat, and will always be sick"... But the poor guy baths through his mouth sometimes when it's bad. I do have him on science diet kitten wet food, and science diet kitten dry food. (My expensive little buddy). I also give him lysine 2x a day, which helps a little, and I gave him chloro*****, its an allergy pill the vet prescribed but I forgot to spell it lol. It doesn't seem to help a great amounts any more.
His name is Snarf, and he is a little love bug. Sweetest cat I've ever had, and I've had a lot of kitty's lol. I'm really at a loss bc the vets don't know, and I sure as heck don't know! Any thing out there that can help boost his immune system more than lysine? He has had ALl his shots and is always up to date. Loves food..... LOVES it. Any help or advice would be greatly appreciated!!! It's tiring cleaning his little nostrils many times during the day with the warm q-tip and saline nose drops! Lol
Thanks!!

Have you tried Famcyclovir?? It is an anti-viral medication. I use it for my kitties when they have flair-ups. The medication can be a bit expensive ($130 for 30 pills) but they take 1/2 a pill every day (every other day on maintenance.)

Hmmm money isn't an issue, it's crazy to say that but I just want him to be comfortable. Where am I able to purchase it? Do I need a prescription? Thank you

It is a prescription called in to a regular pharmacy. Where I live, there is only 1 pharmacy in about a 100 mi radius that carries it (a 24 hr CVS.) I'm lucky that that pharmacy is only 15 mins away. But, it took calling each individual pharmacy to find it.

Ask the vet to do a culture and sensitivity test on any nasal discharge.  There might be some kind of infection that is sort of being cleared up by the antibiotic, but once stopped, the infection comes back.  We went through this for 8 months with  my Hannah several years ago.  Finally found a vet who suggested the C&S and found the underlying infection.  The culture will tell the vet what kind of infection you're dealing with and the sensitivity test will tell the vet which medication will best treat it. 

You can also give your kitty an antihistamine.  I use Claritin (loratadine) for Hannah.  She gets 1/2 of a 10 mg pill once a day.  It really helps with her allergies and sneezing.  I also give her 500 mg of pure evening primrose oil once a day to help decrease inflammation.

Switching to a grain-free diet might also help as will adding L-Lysine, 1000mg daily (500mg twice a day) during a flare up episode.  You can decrease it to 500 mg daily once things are under control.  You can buy Lysine tablets at the health food store or in the supplement section of Wal-Mart.  I buy the 1 lb. powdered NOW brand container or VitaCost container online, but if you've got a health food store near you, they may carry it.  1/4t is equal to 500mg.  I add it into wet food with just a bit of water added and the powder dissolves.  I also add the Claritin and EPO to Hannah's wet food mix. 

Thank you both, I am going to make another appointment with my vet ASAP. I just purchased a nasal aspirator to suck his big boogys out. Lol I have primrose to induce labor but its the liquid gel. Is it okay for snarf whose a male to take it?
I'm also going to talk to vet about the herpes... The sores in his mouth make me nervous!!

It needs to be pure evening primrose oil.  You can use the stuff in a gelcap.