Hi again,
This type of swelling may also indicate a sinus infection or other problem in the sinus cavity, and because you now mentioned his eye is looking 'cloudy'--does it look like his third eyelid is coming out from the inside corner of his eye and covering the eye partially or totally? If so, the third eyelid shows when there is illness in the body, and/or there is a specific eye problem.
The teeth, sinuses, eyes, are all in this 'shared' area, so the problem has to be located by the vet in order to have it treated in the best way possible.
I can't tell you how much it would cost, because it depends where you live and what has to be done at the vet's. Initially, an office visit should be all you have to pay for. Here are some websites with helpful information in finding lower-cost vets. Some might even treat your cat 'gratis', if you have extenuating circumstances:
http://www.uan.org/lifeline/guidelines.html
http://www.fveap.org/sys-tmpl/door/
http://www.hsus.org/ace/11875
http://www.carecredit.com/
and this one contains links to other sites:
http://www.vvma.org/finast.htm
Also, inquire at the vet if they will accept installment payments over a period of time to make it easier for you.
Please keep me posted.
Cher
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