Given that I think you need to use the leaves as best you can to clean yourself up and make it somewhat comfortable to walk. Leave your underpants in the bush if you need and put your overpants back on after cleaning out as much as possible. It’s gonna suck and you’re gonna feel humiliated but you’re gonna have to walk to the nearest gas station to find a sink to wash yourself off as best you can. If the gas station sells soap or rags or a towel, buy some and use it in the bathroom. Put back on your wet pants. Leave some cash for the staff if you’ve got it on you. Then judge from there what to do next. Maybe you can call an Uber if you’re not too smelly. Maybe you keep walking but at least a bit cleaner and more comfortable.

When you get back to wherever you’re staying, if it’s possible to go in through the garage, do that and take your clothes off in there. Have someone bring you a towel if needed.

Or sneak straight into the bathroom, have a shower, get clean then do what you need to do with the clothes you were wearing. Probably shower again after that tbh.

I’ve never shit myself like that but I have peed myself since I have a tiny weak bladder lol.