Hello, You have not mentioned what medication you have been taking. Take water, fluid, soup in adequate amount to prevent dehydration that may be causing dry mouth. You can take vitamin E rich food in your diet regularly. You can also take vitamin E, Evion 400 caps, once daily for 10 days to get rid of dry mouth. Swollen knees are indicative of developing arthritis. Avoid sedentary lifestyle and do exercises and walking. Never take medicines in empty stomach, it may cause pain. Burning pain is indicative of gastritis or acid reflux, take antacids or PPIs to get relieve. Include fiber in the diet and avoid constipation. If needed, you can take laxatives at bedtime for better bowel movement in the morning. Get clinically examined by a GP, get required blood tests and imaging tests to detect arthritis or gout in your knees. You will be treated with conservative treatment and physical therapy. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K, General & Family Physician