Today one of my guinea pigs has diarrhoea, but the other one hasn't! What do I do, I am thinking maybe it was the apple I gave him yesterday, though he hasn't had it today or maybe I am feeding too many green vegetables?. Shall I just not give him vegetables in the morning and see how he is when I get home from work tomorrow? he seems to be running around OK, I have cleaned his bum, but do i keep them both together tonight or split them up if he has a bad tummy? they are both male...I just think it's strange why one has it and the other doesn't! please can someone advise me?