Hello,
Poor little guy, I agree, the superworms are the most likely culprit. Though, it still could be a touch of calcium issue too. Are you going to be giving him calcium daily now?
If the basking light doesn't say Powersun on it which is the Zoomed Mercury vapor bulb. It should be either a 100 watt or a 160 watt if it is the Powersun. As suggested the Reptisun 10 tube bulb or the Arcadia D3 12% tube bulb either one are great.
Let us know how he is doing.
Tracie