First thing to do is get a fecal (or another fecal if you've had one done) to test for parasites. Ask that the fecal include a test for giardia. Rule out that as a cause of the gas/diarrhea/smelly poop.
The Wildtrax has calcium carbonate in it so you don't have to worry about supplementing with calcium.
To ensure proper balance of vitamins/minerals, it's best to feed one type of meat at a meal. If he likes beef, mix in a bit of beef liver and beef heart. I buy a whole heart at the grocery store, cut it up small portions and freeze it. Same with chicken hearts -- I freeze 4 in a bag to mix in with chicken & turkey.
Don't feed chicken breast -- use thighs and legs for higher taurine value and higher mineral content. You can buy regular grocery meat if you that's what you prefer.
It is important that you follow the guideline for ratio of meat/organ/bone. You can give him chicken necks, wings, ribs with meat on. Also cornish game hen. Turkey necks & wings are good too. He won't be able to chew the bone, but it'll be good for gums and teeth.
So the ratio for feeding each week:
- 80% raw boneless meat. This includes primarily muscle meat but can also include things like fat and skin, along with any kind of connective tissue such as tendons, sinew, cartilage etc.
- 10% raw edible sized meaty bones (necks/ribs/wings)
- 5-10% squishy organ meats, with half that amount being liver. Don't overdo the liver -- it'll cause diarrhea.