The tip of my elbow hurts very much if i lightly touch it or do anything else to it. the only thing that might have caused this was tennis.

Tennis elbow.: Tennis elbow is common especially in tennis players. It causes exquisite pain near the tip of the elbow that gets worse when the wrist is held in a cocked up position against resistance.

Tendonitis: The most common causes of elbow pain involve tendon inflammation or microtearing of the tendons on the outside of the elbow (lateral epicondylitis) or the inside of the elbow (medial epicondylitis). Treatment involves rest, a wrist splint, icing and nsaids for acute cases. Injection therapy is often effective. Steroid injection for acute cases, platelet-rich plasma for chronic cases.

Olecranon: The tip of the elbow is the olecranon and if the pain is right there it could be an olecranon bursa some of these can be seroius if they get infected which is not uncommon if it persists you should see an orthopedist.