Similar to malocollusion in chinchillas, my gecko didnt get enough vitamins and calcium so her bones became too weak and she couldnt move so she died. Infact I accidentally killed her by feeding her on the tip of her nose. When she went to lick it she couldnt swallow and choked.
Its very very very hard to tell if a reptile is sick until its almost too late. If they are less active or regurgitating thats a sign. You might want to take the gecko to a local vet OR to a reptile specialist and just ask.