Retire would be the best option for him and the Team.

Has he been suspended though? I haven't heard anything.  We don't know what has caused this sudden decline in his mental health. Maybe he has issues at home. Either way, we don't know and won't know. We can only hope he's okay now and he does what's best for him and the team

... or call the next few matches off until he's ready to return?

The only report I've seen mentioned him getting something like 4 bonus points in an early season match. I'm presuming the above do not include BP's? 

Not a great many options to replace Castagna, maybe give MPT a 28 day contract, see if he can impress? If he doesn't bring Paco back. 

I think he will tbh Gavan but Doyley's NSS average will be a lot lower than Bewley's imo.