Hi OP

I'm not sure if this could be classed as advice, I'm just suggesting what I would do in the same situation. I'd just ask him why he needed to change clothes/turn the telly on and off again/whatever and go from there. It might be an assurance thing (and I feel as though you're a bit worried about OCD, anxiety or similar?). Perhaps prime him with discussions like, "we're going to go and play in some puddles. We'll probably get a bit dirty, and after we've finished playing we can come inside and change out clothes." This gives him parameters and something to focus on, rather than freakin out as soon as he's dirty (and not knowing how long he will be dirty for).

Regarding the schedule: it might be that he feels more confident when he knows what's going to happen. Perhaps talk to him about what is planned for the day, but also talk about how you can deal with change if that happens too.

Hope this helps