I would try Promaxol to reduce the pain. It contains the stronger LM potencies. It can be used with conventional prescription medications. You cannot use human pain relievers for your cat. Your veterinarian would need to prescribe something that he or she believes best addresses your cat's type of pain. In order to avoid having your cat be too lethargic, I would use a combination of Promaxol and the drug your vet chooses, such as Tramadol, using the smallest dose of Tramadol that provides a suitable level of comfort and still allows your cat be alert enough to enjoy life. By using the combination hopefully you will reach a good comfort level with just a small dose of the drug. Try Promaxol alone first and add the drug if needed.
In addition, it is helpful to give digestive enzymes with each meal, probiotics, and fish oil. The oligotherapeutic mineral base found in the IonX products helps the body to better utilize the other nutritional substances. Giving nutrition and avoiding toxicity helps with quality of life and longevity. Also, be sure to give sufficient fresh water that is free of chlorine and fluoride. The other thing that is sometimes beneficial is to have veterinary acupuncture. It can help improve pain and appetite. I hope these suggestions give you a lot more quality time with your cat.