Tennis elbow more commonly occurs from non-tennis activities than not.
It is associated with excess use of the wrist extensors ( those muscles which pull the hand backwards)
These are attached to the lateral(outside ) epicondyle(bump) on the elbow, and thus excess atrain is felt as pain in this region.
Quite commonly it occurs in mechanics who have been using spanners a lot or when someone does a lot of screw-driving activity ( said carefully)
Rest is the most important treatment ( ie avoidance of the activity which caused it).
Physio may help as may anti-inflammatories or a steroid injection.
So called support straps are useless.
See a doctor and make sure you do not have any form of arthritis , eg gout.
Yes gout can and does occur in the elbow.
Cirrus