Twitches

I'm 19 years old, and for over 3 maybe 4 years I have experienced twitches. Usually in the legs or feet, but also in my arms. Before all of this I also had a great memory, but that is changing as well. Sometimes just minutes after a conversation it is hard to tell another person what was said, and I often get confused on what that person meant or wanted. Other changes have also been teeth grinding, laziness, exhaustion, headaches, backaches and extreme hair loss. Does anybody know what could be the cause of all of this?