If she hates going to the vet then it may be that a urine sample might indicate if there are any kidney problems, and this could be taken at home and then taken to the vets and Drum would not necessarily need to go there.
My girl Rosie presented with kidney problems in just this way, nothing untoward except that she was drinking at lot and peeing a lot. The urine test showed that she had protein in her urine and needed medication.
Lewis, my rescue boy drinks and pees a lot. He has done since we got him 8 months ago, even though his estimated age is only 7. However he has had a tough life. The vet tested his urine - it was very diluted (a sign the kidneys are not functioning at their best), but no protein, so no meds for him as yet, though that time may come.