Like you we'd had sheep for ages before we got cattle and their behaviour is quite different, I find. So not a big black sheep. That's what freaked me
After calving, our cows and calves have a wee sleep before getting on with feeding
And calves sleep a lot. They'll maybe only feed every four - five hours. In the wild, the cow would feed the calf, then lay it up in long grass and go off to graze.
Watch to see if she's peeing (must be taking liquid), pooing and he belly isn't clapped in.
Two years ago I had such a panic about a calf I got the vet out. I never saw him feed and his mother had such a huge udder it never looked like it had been sooked. He was fine and this year I was much more chilled.