Stay in contact with your veterinarian if you're at all in doubt about how your cat is handling the loss of his companion. (catbehaviorassociates.com)
That is, thankfully, rare - but stay in close contact with your veterinarian because they saw how many crystals he has and will be better able to give you a prognosis. (1800petmeds.com)
In many cases, this will be the owner's first contact with a veterinarian. (abtaskforce.org)