Thanks so much for your advice. I finally got someone at the rescue to help me get him to a vet, they say it's a side effect from the dewormer and the worms leaving and such, but they gave me flagyl to give him and some bland wet food. I will continue keeping an eye on him, but I was worried...
I recently took in 2 Foster cats, a Mama (approx. 1.5yrs old) and her baby who's about 3mos old now, and after about 2 weeks discovered they had round worms, the rescue I'm dealing with has not been very helpful so needless to say it's been rough...but I finally got meds from them and was told...