Impaction? MBD? Just sick?

Question
My bearded dragon is about 5 years old now. Yesterday he fell off his log, onto his back, and couldn't turn himself over. Ever since then he's been twitching when I touch him along the lower spine and sides. His stomach isn't round, but more triangular. Could this be impaction? He won't eat and before he fell down, he would spit up any and all water he drank. Also, all he eats are the worms I give him, despite me giving him greens such as parsley, kale, spinach, and red cabbage with the worms. He seems weak when he walks, but I don't think he has MBD because he still has full control of his limbs, but I could be wrong. What could all these signs mean?

Extra: The temperature in his cage is where it should be- 100 on top, 95 at the surface. He has a UVB light on the left side of his cage. He lives in repti-sand.

Answer
First of all get rid of the reptisand. How old is your UVB light, and what brand is it?  If it is older than six months it should be replaced.  And it should be a fluorescent tube, best is a Reptisun 10.0, but not the compact.  Compacts are downright dangerous and have been known to blind and even kill many species of reptile.
 Your salad needs help too.  Spinach is a high oxalate and literally binds calcium so the dragon can't use it. Parsley is even worse and kale and red cabbage causes gas.  He needs collard greens, mustard greens, turnip tops, dandelion greens, arugula, or mache, at least three of these, plus sweet potato and winter squash.