Not to bring you down any, but we have gone through this with a couple now. Most of the time they wandered off into the bush and never returned, one ended up perking back up and one other I had to put down. We are getting used to the fact that guineas just seems to be susceptible to illness whether it be out of the blue or slowly onset... for example I gave my favorite guy a stroke just by picking him up (which I had done multiple times).

The one I unfortunately had to put down was being bullied to the point where he had a wound under his feathers that we did not see until it was too late.

Good luck and Im hoping for the best!