I would try PROMAXOL to help with the discomfort. It helps to decrease pain, inflammation, and stiffness and stimulate healing. Initially I would give 5 drops with breakfast and again at supper. If needed you can give another 5 drops at bedtime. After improvement is seen you can decrease to a whole dose once daily. For longer term management you can switch to ARTHRO-IONX. However you can just start with ATHRO-IONX if you prefer. In addition I find it helpful to follow a holistic approach by giving nutritional supplements to accompany the homeopathic. I would also use PROBIOTICS and OMEGA 3,6,9 to reduce inflammation and strengthen the body.
What type of food and water are you giving? These too make a difference.
It would also be beneficial to have an evaluation done by a veterinary chiropractor. When the muscles tighten up it can put the bones out of alignment. From the symptoms you describe I have found chiropractic and acupuncture to be helpful.