My mother-in-law began having the same symptoms you describe around age 50, but she was a heavy smoker so all assumed her dry eyes and mouth were due to that. A year or so later she began having pain when walking up stairs and in hand joints, Sjogren's drys out the joints, but she assumed it was arthritis. She was in the early stages of Sjogren's a disease we had never heard of before. Even if you don't have Sjogren's be sure to keep your mouth lubricated as it led to her beautiful teeth being destroyed and she eventually had to have implants.
After diagnosis she was sent to a Sjogren's specialist at Script's in La Jolla CA. He told her he wouldn't treat her unless she quite her smoking (3+packs a day) because that drys the mouth and aggravates the disease. She was furious, kept smoking and Sjogren's wasn't the cause of her death, it was lung cancer at age 70.