I have a 10 yr old male cat who has been on Fancy Feast Classics for almost 4 years to manage his blood sugar. He has been doing wonderfully until just last week he has spiked to 110-150. He was 110 before feeding and 155 after. Any ideas?? What can I do? I thought maybe he snuck into the pantry and ate some dry food for our other cats. Is it possible he is just relapsed?