Take it from me, mealworms aren't a good source of food for uromastyx (they especially aren't good for bearded dragons also).
Mealworms have a chemeical in them called critin ( I believe that's how you spell it). But its in their shell and it makes it real hard to digest them. I suggest if you do feed your uro any insect it be either crickets or wax worms and even then only 1 time a week and not a whole lot (maybe about 10 crickets, or 3 wax worms).
You could try putting bee pollen on his greens and see if he eats. I hear that it stimulates appetites in our uromastyx's.
Good Luck and I hope everything turns out fine.
PS: Never EVER feed superworms to anything you own, I accidentally did that with my bearded dragon Hades and he almost died as a result of their hard shell (I thought it was ok because I read it on a couple bearded dragon sites, never trust sites unless you know for sure the person is an experienced bd breeder).
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2 Mali Uromastyx-Ares & Apollo
2 Bearded Dragons- Draco & Hades
1 Saharan Uromastyx-Iris
1 Leopard Gecko-Kalypso
1 Tokay Gecko-Sid Vicious
1 Tarantula-Peter Parker
1 Amazon Red Head Parrot-Pancho
1 African Gray Parrot-Keya
1 Dog-Cheeka
3 Fish-no names
1 Beta Fish-also no name
1 Zebra Finch-Beeps (we used to have 5, but some went on a killing spree).