Not much a fan of headcollars and gimmicks myself. If a dog isn't doing what I want then I try and figure out what I'm doing wrong!
At five months, losing focus is not a big surprise, that's why your training him. But If you need that "crap" to walk him then that's probably, your first step in the new dog process,ditching it. I gave "my" opinion on "gizmos" so you can infer from that what "I" think of your trainer.
Notice on the video I posted..no gimmicks for the walking and treats not toys were used. Some dogs will work for toys some won't. Yours seems to indicated he won't? Why are you still using it?
Your "thinking" about what you're doing and that's the most important step! Give this a thought also.