Hi, welcome to the ehealth forum and I am glad to help you.
You seem concerned by the pain in muscles and joints every couple of months and lasting for 3 days or so.
You might be having the fibromyalgia syndrome. Fibromyalgia syndrome (FMS) is characterized by widespread pain and fatigue. Fibromyalgia means pain in the muscles, ligaments and tendons - the fibrous tissues in the body. Viral or bacterial infections, automobile accidents, or development of another disorder, such as rheumatoid arthritis, lupus or hyperthyroidism can bring about the onset of fibromyalgia. The diagnostic criteria for fibromyalgia are still debated.
You must see your physician for definitive diagnosis as the same cannot be made online.
Hope this helps. Take care.
Note: This post is not to emphasise final diagnosis as the same cannot be made online and is aimed just to provide medical information and no treatment suggested above be taken without face to face consultation with health care professional.