What might be causing these symptoms?

Actually, I have astigmatism and have worn gles or contacts since I was about 12. I have had some of these symptoms so far as the dots and shooting stars. From what I understand these are called floaters and there really isn't anything that can be done about them. The muscle twitches and jerks are most likely due to eye strain. Do you work on a computer much? Even the headaches could be caused by eye strain. I have also heard that dry eyes can cause some of these problems. I would find a really good opthamologist and have a complete work-up. I hope I have helped! Good Luck!