My vet considered it for interstitial cystitis for my boy, but we tried changing to canned food and that solved the problem for him. She said it is used in chronic pain syndromes and behavior problems and it is somewhat sedating so it is given at bedtime. Becky
You might try just continuing to give it and see if she is able to adapt to it. Amitriptyline is a drug that can cause a lot of sedation at first, but after a few weeks the sedation is less. Just be sure to communicate with your vet about it, because she may need a lesser dose than the average cat, and give it a bedtime. Also, you need to make sure your vet checks her liver enzymes a month after starting and at least yearly thereafter, although I would want it done more often. If it is improving her hyperesthesia, and nothing else has worked, then it is worth giving it some time to see if the sedation improves. Hissy wrote an article that may be of interest. Feline Hyperesthesia
Becky