Kitten with sagging belly

I have a 4 month old kitten with a very floppy/saggy belly.  She is not overweight, at her last vet visit I was told she was actually slightly underweight.  She had coccidia (worms) that gave her a swollen belly, but now the coccidia has gone she is left with saggy skin.  She has also been fixed.  I have seen this in older cats, but not kittens. Is this sagging belly issue normal in such a young cat?