My older cat won't stop marking!

I have a 6 year old female cat and a 6 month old male cat. They are both fixed and declawed. We got the younger cat when he was 5 weeks old. All was well until we neutered and declawed him. Now the older cat wants nothing to do with him. She marks in the same spots since he came home from surgery. This has gone on about 4 weeks. Ive used enzymatic cleaner to clean the urine and odor. Ive used cat pheromone spray in the areas she marks. The 6 month old is business as usual, but the 6 year old does not tolerate him. If anything, the baby aggrivates the heck out of her now. To top it off, I am 3 months pregnant and can smell like a bloodhound. My happy 2 bedroom apartment home is in chaos. Im miserable, the older cat is miserable, and my husband and the 6 month old are just fine. I really dont want to get rid of the kitten but dont know what else to do. Any suggestions?
P.S. Getting a bigger place isnt an option until next year.

Hi and welcome.

First, are you absolutely sure she is 'marking'? There could be multiple medical reasons that a cat suddenly begins peeing in places she did not before, and since this behavior seems new/sudden I would recommend going to a vet to rule out a medical issue that happened to coincide with the kitten's reintroduction to the house.

If it is behavioral, it sounds to me like what may have happened is that when your kitten came back from the vet, your cat didn't recognize his scent and identified him as a stranger.  She then got territorial for some reason.

What I'd recommend in that case is a complete reintroduction of the cats, exactly following the steps in this article: http://www.thecatsite.com/a/introducing-cats-to-cats

As a side note, while it's done now, this site is strongly anti declawing.  I hope that if you get more cats in the future you will research this practice fully and not subject another cat to the procedure.