It is important to understand that too much exercise too soon with the green flexbar can actually lead to the frustating situation of not improving your pain, or even making it worse!
What is likely happening at tendon level is that there are multiple small tears in the tendon:
Now most of us have seen a wound in the skin heal over in week.
But skin is a special tissue that heals quickly.
Tendon on the other hand, takes a LONG time to heal.
Tendon heals by the body making little threads of protein that look like a spider's web.
Just like a spider's web, these protein fibers can easily be disrupted by too much movement, never mind vigorous exercise!
So it takes many weeks for the body to weave these individual fibers into a strong tendon, that almost resembles a braided rope:
During the most active phase of healing (inflammation) the body is making lots of chemicals (cytokines) to initiate and promote the healing.
Unfortunately those chemicals also irritate delicate nerve endings, causing pain.
But pain then can become a valuable indication of how much activity/exercise you can do.
So first, REST until the pain improves.
Then the principle of rehabilitation done by all physical therapists is to very gently begin moving the joint involved.
If pain recurs, or worsens, the exercise must be stopped, and not start until the pain lessens.
I would highly recommend starting exercise with a red Theraband Flexbar.
It probably would seem like only a "wimp" would use one so easy to flex, but it is the one used in the big study on tennis elbow.
The red is designed to do the "Tyler Twist" without disrupting the healing fibers in your elbow tendon.
Once you can do the exercise with the red for a couple of weeks, only then should you move on to the green.
Again start gently or risk tearing the fibers apart, and have to start healing all over again.
After a few weeks using the green, begin to incorporate in the exercises in the Thrower's Ten Exercises: http://www.muhlenberg.edu/pdf/main/a...throwers10.pdf
Only after all of this should you return to gentle short hitting sessions, gradually increasing your hitting force and length of your practice sessions over time.
By taking this step by step approach you should be able to return to tennis actually much faster than those who return to soon, tear all the healing fibers, and have to start all the healing all over again.
Check out the multiple long threads here in this section of those who tried to return too soon, only to lengthen their misery.
I hope this helps.
I wish you the best.