It sounds like you might have skipped some steps in handling the treats and now he is dependent on them. I'm not sure where you've gone wrong/how you handled the treat/reward training so, I'll recap the basic process:
Treats are an excellent way to lure the dog quickly into the position(s) you want where you immediately reward and praise.
Once the dog understands the command (sit/down/come, etc) you start varying the timing of the reward....treat after 2 repetitions, after 3, after 1, etc. In conjuction with the variable schedule, you also slow down the delivery of the treat...no more 'rapid firing' of the reward.
Next step is to add a 2nd exercise ie; a sit plus a down and then treat. Then, add 3 exercises and treat, etc.
To continue the weaning process, you no longer carry the treats....they're left on a table or a chair. Both the two previous steps and this one teach the dog to wait for it (delayed reward).
Too often, treats end up being used as bribes (do this/that and you get a treat).