Things Fall Apart Before Trial

Not unexpectedly, things are falling apart a little before our first open obedience trial. I have been weaning Wyatt off treats and lots of verbal praise in anticipation of our upcoming Open A obedience trials. For whatever reason - probably the weaning off of treats and verbals but also possibly in my tone of voice or stress level - Wyatt is having trouble with heeling of all things, which has been very solid for at least a year. I am seeing lagging, not going with me on the heel command, and no sits. I am going to back up and give more treats or verbals if he seems stressed and also back up to 2 exercizes and then a treat.