My poor kitty is just miserable

2 weeks ago he had many of his teeth extracted.  He was coming along nicely and got hit with a URI.  For a while I did think he would make it he looked so sick.  The vet says his lungs are clear and its all in his nose and sinus.   Today is the first day he has been able to nasal breathing but not really well.  Its very noisy but so much better than watching him breathe through his mouth.  

The vet has him on Doxy but I think this is probably viral   I know when I took Doxy it made my stomach feel bad and Im wondering if thus why he won't eat.

I feed him watered down cat food with a syringe and I also give him several syringes after the Doxy in case its burning his throat.

What else can I do for him?

I have amoxicillin I could switch him to but I don't know if it will work on what he has.

I keep him in a room with humidifier several hours a day to try and loosen up the nasal passages.

Can I give him an antihistamine to help dry this up??   I just have a bad feeling about the Doxy, but maybe its my imagination.

Any ideas ?

My vet recommends either Benadryl or children's liquid Claritin (loratidine). BE warned that Benadryl foams up in a cat's mouth and most cats that I've ever seen find the experience very distressing and frightening. So I stick with the Claritin.  You could also try to consult a holistic veterinarian and ask about herbal remedies, including using L-lysine and herbs such as slippery elm bark, marshmallow root and licorice root. Poor kitty - sending prayers and vibes that your cat makes a complete, speedy healing!

Thank you for the Claritin  info.  Does anyone have an opinion on switching to Amox.    I just keep thinking it may be the Doxy thats keeping him in such a depressed mode.  He looks like he is dying even though his breathing has improved a little 

How long does a URI take to run its course?  He's had this for about 10 days.

I prey its not the  Doxy thats upsetting his stomach or irritating his throat  

I don't know how much food a cat needs to stay alive but I don't think I get more than 2 or 3 teaspoons in him each day

I have had him on lysine for most of the 10 days he has had this.

I am fostering a 4 1/2 old kitten. He came to my porch about 2 months ago. My problem is that he agressively likes to suckle. He likes my hands and fingers. If I discourage him, he gets even more aggressive. This happens several times a day every day. Any advice?

As soon as he latches on to your fingers give him a soft toy to suckle on or a piece of old blanket.