eight month old puppy issues

hi all! so i have an 8 month old husky x great pyrenees that im having some issues training out. he’s majorly in that eight month fear period and i cannot even get him to function. yesterday, he slipped his martingale (it got bumped to be too loose) because of a pumpkin decoration in someone’s yard, ran across the street and froze. he’s just been so stubborn and will not listen to a word i say. i’m going to be reaching out to a professional trainer when i can afford to but i need to know how to get by for now. he will not come inside when we need him to, nor will he listen to a word we say, even with high value treats. he’s a service dog in training and i feel like we are losing valuable time when he is struggling like this. he’s always behaved so well and been an incredible listener since we got him at 11 weeks, but this is such an incredibly frustrating scenario. we have had a full medical evaluation done as well and all checks out great there. thanks all and im looking forward to good insight!