Undifferentiated connective tissue disease is a "waste basket diagnosis" -- meaning a diagnosis we make when your symptoms do not fit a known pattern of a connective tissue disorder. This can result in sever problems to one's health and well being. As such, I would recommend that you discuss this fairly complicated issue with your primary care physician
. In addition, you may require the advice of a rheumatologist
-- a doctor
who specializes in connective tissue disorders.
Connective tissue disorders are disease of the muscles, joints, ligaments etc. These are often systemic disorders -- meaning that they affect they entire body. The most common mechanism is that of autoimmune abnormality. This is, as you suggest, when the body develop antibodies (attacking proteins) against itself -- instead of against a bacteria or other infecting agent. These float in the blood and can cause problem in many tissues including the muscle, skin and internal organs. Most of them follow a specific pattern, thus a specific diagnosis like lupus or scleroderma or rheumatoid arthritis can be made. However everyone is different and disorders that have similar characteristics but do not follow a known pattern are called "undifferentiated."
Treating these disorders is possible. Often medications to fight the immune system (like steroids) can help. That being said, the diagnosis needs to be confirmed (some infections or cancers can look like this). Subsequently, a rheumatologist may start you on some medicine.
Talk to a rheumatologist.