What kind of frog is he? Grim FrogBreeder is right it could be natural color. As for throat/belly, can you post a better picture of that area? Frog's fat kinda covers it up XD
Hes a Carnwelli. The pink in the leg is normal as he as always had that. In the pictures posted you can see the redness as I am talking about in the belly/throat its subtle (not as pink as the legs)