Get veterinary care for Felix

Our cat, Felix, is very sick, and we don't know what is wrong with him. He and our other two cats had tapeworms in early January, which we treated. However, as the other two recovered, he began having diarrhea and started losing weight. My husband took him to the vet on January 25, but we couldn't afford any testing at the time, and the veterinarian told us that she couldn't find anything wrong with him. 

Since then, we have tried changing his food, giving him Pedialyte to rehydrate him, giving him feline probiotics, and feeding him high-calorie nutrient gel for cats. He has continued to have diarrhea, he is very lethargic (before this, he was extremely lively and playful), and he is frighteningly skinny now. 

We were trying to hold out until we received our tax return so we could get him the care he needs, but it is delayed and we may not get it until February 27. My husband just switched jobs, and he had to go a week without work in between, so we are also down a full paycheck, when we already live paycheck-to-paycheck. I am disabled and unable to work.

We are really desperate to get Felix seen. We love him so much, and we are both sick with worry about him. He is only about four years old, and he is too young to be so sick. We are asking for $1000, because we aren't sure yet how much it will cost to get him treated, but we do know that individual tests, like fecal testing costs several hundred dollars alone. If you can help even a little bit, we would be incredibly grateful. 

Thank you,
Karyn & Jonathan