It likely is "tennis elbow" or "golfer's elbow". [Yes, golfer's elbow is quite common in tennis players.]
Which tendon insertions have the small tears determines whether it is tennis or golfer's elbow.
With the palm up, "tennis elbow" occurs from tears in the tendons on the outside (lateral aspect) of the elbow, while golfer's elbow occurs on the inside (medial aspect) of the elbow.
Tendons are the strong fibrous tissue at the ends of muscle that attach a muscle to bone.
Tennis and golfer's elbow are overuse injuries.
Bashing a tennis ball involves extraordinary force being exerted to the tendons inserting to the bones at the elbow.
Tiny tears develop in the tendons.
The body is busy healing these tiny tears by laying down protein fibers to fill in the defects.
But if you play too much, especially if you use a stiff racquet and/or strings, the body can't keep pace with filling in the small tears with new protein strands.
More and more tears occur.
Your tendon looks like this:
Inflammation is the first stage in healing.
Inflammation gets our attention because pain is involved, but pain is just a byproduct of the chemicals (cytokines) being released to stimulate new protein strands to be made.
The main job of inflammation is to stimulate those new protein strands to be made to plug the tears.
Stopping to play for a few days often makes the pain somewhat better.
But a few ways is way to short for any real healing to occur.
The new protein strands being laid down look under the microscope a lot like the strands in spider's web.
It is only after these strands become cross linked and remodeled by the body do they form enough strength to withstand the forces involved in bashing the fuzzy yellow ball.
[Collagen is the name we give to the protein strands when they are organized to look more like rope or cable, and tendons are made up of bands of collagen.]
So do yourself a favor and rest from tennis for a few weeks to let the process become started.
Buy a red Flexbar and do the "Tyler Twist" exercise to slowly start to rehab, and to invoke the very light mechanical load on the tendon that will help to orient the direction the protein strands will become organized into.
Thera-Band FlexBar Video Demonstration http://www.youtube.com/watch?v=zB3TVb8a5mk
If it hurts using the Flexbar, wait longer for more healing to begin before starting the exercises again.
Only after you have been doing the exercises for a few weeks without pain should you consider returning to tennis.
Otherwise you will tear asunder all the healing that has already happened, the tears will reopen, and you will have to go through the whole process all over again.
I hope this helps.
[By the way, what type of strings do you use? Do you do off court conditioning of any kind? The Prestige S has a fairly good flex rating (63), so I doubt this is the main problem. Still, there are even softer frames out there if the problem persists, like the ProKennex Heritage Type C Redondo Mid with a flex rating of 56. And are you sure there are no problems in your technique leading to undo stress at the elbow?]