Clearly you are a guy of extreme responses, but quitting fishing is going a little far. 

 PRP therapy is a variation on autologus blood injections, whereby instead of blood being injected into the naughty tendon, it is refined into a solution that is higher in platelets. There are no studies to suggest one method is more effective than the other, or in fact that either is particularly effective by itself. Currently there are some fairly low-quality studies and a bunch of anecdotal evidence that suggest improvement rather than resolution of tendonosis. If you have a predilection for needle-stick medicine, I would try voodoo first.

Keep in mind that you are attempting a lazy solution. Or someone doesn’t know their exercise rehab. Or both. I agree with said doctor that lateral epicondylosis in its more common incarnation is unlikely; i.e., tendonosis of extensor carpi radialis longus (ECRL)—the long muscle that extends your wrist on the thumb side—is not the culprit. The position you have marked on the image is over the supinator. Does it hurt to supinate your hand against resistance when the elbow is straight or slightly bent? Take someone’s hand as though you are going to shake it. Now try to twist the person’s hand such that it is on the top while he resists at about 80 percent (i.e. you will win against the resistance).  

It is thought that an injury to the wrist, which can be as minor as a sprain, pinches or severs the blood supply, but in a significant portion of cases no injury event can be identified. Progression of the disease is virtually always treated with surgery unless you are an Oompa Loompa, in which case it is microsurgery. If the condition is a tendonosis you will get pain doing specific movements of your hand or forearm that tend to diminish as the tendon warms up, but return soon after you finish exercising. The trick is to isolate that movement and tailor an eccentric exercise program to strengthen the tendon. Everything else is a trick that will end in a trail of tears. You can read about more common versions of elbow tendonosis and how to cure them at www.drjuliansaunders.com/resources/.

Without a definitive diagnosis (and your pain may not even be tendonosis, let alone the type I have suggested), moving forward is akin to revving your engine in neutral—not likely to end in disaster but, not going to get you anywhere, either.  

If your guy can’t diagnose the issue, an MRI may be a convenient, albeit pricey, shortcut. Certainly, this doesn’t sound anything like what a practitioner would routinely see in practice.

Julian Saunders is a registered D.O. His advice is to take anything he says with a lick of salt, followed by the best tequila you can find.