Cat has trouble breathing after eating and has lost a lot of weight.

We noticed our cat was breathing heavy almost a month ago, and took her to the vet. They took her blood and took X-rays. The vet thought it might pneumonia, thyroid problems or cancer. The results all came back negative and the vet suggested we see a cardiologist. They thought it might be asthma and gave us steroids and antibiotics to give her. These don't seem to be helping her at all. We have tried giving her wet food but she directly after eating she starts breathing very heavy and just lays on her side by the food bowl. We have found running a hot shower (our bathroom is connected to our bedroom) and putting her up on the bed so she can breathe in the humidity seems to clear up her heavy breathing. Has anyone ever seen this before? Our cat momo is about ten years old and has always been skinny but has lost a lot of weight since this started.

She also breaths very heavy after eating dry food as well.

You must be really worried about her, I'm so sorry this is happening.  Have you taken your cat along to the cariologist yet?  If so, what did they say?

I've not experienced this before but it they're not finding any results from the tests your vet has run, and the cardiologist hasn't found anything either, wondering if there is anything with the food that is differnet that she might have a reaction to?

Has she seen a cardiologist?  Has she been tested for Heartworm Disease recently?

Yes she has see a cardiologist they think it could be asthma and have us giving her steroids to give to her twice a day to open her airway. Any activity (eating, drinking using the litter box) seems to take all her energy and she starts breathing heavily and making wheezing noises. The only thing that seems to help is the steam from a hot shower, we are planning on buying a humidifier to help too. I was just hoping to find out why the littlest amount of activity seems to drain her so much so we could get her better.

My boy Munchie has asthma, he is on a steroid inhaler (flovent) twice a day with a rescue inhaler as needed (usually once every few weeks or so), before he was diagnosed he would get winded (just like my hubby does) after any exercise or exertion.    Here are a couple of websites that helped me figure things out for my boy.  http://www.felineasthma.org/   & http://www.fritzthebrave.com/