You might want to start thinking about his sensory and emotional needs.

Many individuals have difficulties with loud noises or harsh sensory stimuli in public. His behaviours, while looking bad on the outside, could be his sincere effort to distract and regulate himself in the face of a very stimulating sensory environment.

Start with finding out from him what are the things which are causing him to feel so bad while outside, and find some ways and strategies to help him to cope with his surroundings.

All the best!