My Dog A Multi Poo Is Not Acting Himself He

My dog a multi poo is not acting himself he is very lethargic and refuses to go potty on Saturday we had a BBQ and I think the kids gave him meat and hot links on Sunday he was fine so we groomed him Sunday afternoon Sunday night out of nowhere he became lethargic he has eaten today but is still very lethargic and has not pooped I do not have any money or I would be at the vet's office right now what can I do