I evacuated with my 5 cats and this hotel room is infested with fleas. One of my cats had the worms that they get from fleas about 4 months ago. My vet charges about 50 to give them the injection that treats this type of worm. I cannot afford that right now as I’ve already spent almost $1000 on evacuation coasts. Is there a good medicine for this that I can buy at walmart? any help is appreciated.