My name is John and I work as a physical therapist in Auckland, New Zealand I recently produced www.tennis-elbow-cure.com to help you overcome this painful condition. In spite of its name it can be caused by repetitive light use, like using a keyboard, as well as vigorous activity such as tennis. People increasing the use of their wrist and hand or playing more sport are particularly susceptible to tennis elbow.
I also got this infographic made to help you diagnose if you have this condition.
I hope it helps!