Never heard of Leos soaking for pain. I believe that your gecko is soaking to cool off. In a ten gallon all you need is a heat pad. That should raise the ambient temp about 10 degrees unless it's cold then a heat bulb can be used. The heat pad, ceramic Bulb and heat from sun is too much shut off the ceramic Bulb and move him from the window.leos don't need sunlight they are nocturnal.

I fed all my Leos a staple diet of mealworms. It is important to gut load (feed) the mealworms. I used a product called "cricket gummies" what the mealworms eat is what the gecko eats . In the mealworms dish i put a 50/50 mix of calcium and vionate ( available at any pet store or online ) do not put straight calcium in with the mealworms it will suffocate them. Do put a small dish of calcium so the gecko can supplement it self.

The reason I went through all that is because your gecko doesn't have a deformity it has metabolic bone disease aka calcium difficency . Causing soft bone.The seller sold you a sick gecko

Get that shed off the toes or they will fall off
Humidity is very important for shedding mist the tank or keep a humid hide to aid in shedding

Hope that helps Kirk