Cat Lethargic

Question
My cat was acting a little strange but I then noticed fleas and figured it was the cause of her odd behavior. So I took her to the vet and she received a dose of Revolution and a dose of Capstar for the fleas. While there she also received two vaccines and the vet says she heard a heart murmur.

I got her home and it's been almost a week now, but my cat's odd behavior hasn't changed at all. She's lays in one spot all the time and it's a spot that I never noticed her lying in before. She used to roam the house and come lay with me on the couch, but she doesn't do any of that anymore. She just sits or lays in that one place.

I am worried about her. Today I just thought that maybe it has something to do with the Raid Flea stuff I sprayed down to try to kill the fleas. I thought it had all dried before she was allowed back into the house, but maybe not. I don't know.

She's 9 years old. She seems to be eating and drinking (she'll get down from her spot to do that and use the litter box). A few days ago I noticed that it was liked she tried to cough up a hairball but it was just a little liquid, but haven't seen that for a couple days.

What might be wrong with her?

Answer
Without a physical examination and perhaps some blood work, it is hard to diagnose properly over the internet.  I would suggest that you take the cat back to the vet and tell them what is going on.  The good news is that the cat is eating and drinking, which indicates that the cat does not feel too bad.