when it comes to wild caught toads and frogs, they have a very high chance of having red leg. Their immune system may keep it at bay and be unnoticeable but when introduced to stress it lowers the toads immune system and the red leg symptoms will set in. From what i can see it does not seem like red leg but i have never seen it in that particular species so I cant tell. Usually it starts with red and brownish spots on the under side of the frog or toad then its coloration will turn pale. shortly after it will become lethargic and wont eat. that is when the legs will start to turn blood red but usually when your frogs legs start turning red it will be fatal within a day or two. also with my encounters of red leg my frogs did not shed there skin. They lost all there slime and started to dry out even when soaking in water. with toads this will be a symptom you may never see. The coloration of your toads underside looks normal to me however i am not a vet and i am not inclined to make such judgements. But what i do know for a fact that the signs of red leg on the underside are very unique.