I think it may have been a bug, I put them both on bland diet for 24 hours and kept an eye on hydration etc and they’re both fine now.
No blood since, and they haven’t had diaorrhea again.
I hope whatever it is has passed through and is gone.
Oscar didn’t seem bothered by it at all, apart from he kept squatting so I guess he was uncomfortable.
Simba is very sensitive and picks up any tummy bug going around, so I guess if she got it he would too.