Welcome to the Forum Kerry. Here's what I know about Kassina senegalensis, they are terrestrial members of the family Hyperoliidae, reed & African treefrogs. They are from West Africa. Well, that's it. I have included a pic I found on the internet of one. See below.
I am a little concerned about the skinny one you mentioned. I know when I had my blue poison dart frogs together, one of them was thinning out, so I took them to the vet. I thought it might be gastrointestinal parasites, but the fecal sample proved to be clean. The vet said to separate them, because one was intimidating the other. I was taken back by this, as both of them did eat. So I did what the vet suggested and the thin one began to put on weight. Now I am wondering is this the case with your two frogs?