You may have medical issues in your hands, but perhaps if we could reduce the stimulation of numbness by reducing hand pressure, you'd find an improvement.

One of the classic causes of hand pressure is too much weight on the hands. This can be corrected, until you can build up your core strength, by moving your saddle back away from the bars. Eventually your center of gravity will move back so far that you will not have much pressure on your hands.

Another classic cause is to have the saddle nose tilted down. This actually causes you to slide forward on th saddle. Your natural reaction is to stop this from happening, by pressing forward on the bars with your hands - hence, hand pressure! Level the saddle, or adjust it so the nose is a little bit up - better for some saddle designs.

Either of these corrections can make it seem like your leg extension is again not right, so after getting used to these for a few rides, adjust the saddle height again, using the same method, but this time do not change the fore/aft position of the saddle (do not slide it) and do not change the tilt.

Next, try to reduce back stress while riding by trying to make your back straight and relaxed, and by bending forward not in the back, but by folding your upper body forward at the thigh/pelvis joints. This often becomes more comfortable if you have the balance (saddle fore-aft) right. You can even get the feeling you are floating over the handlebars.

When I can adjust to achieve this position, I feel pretty darn good! If you can do all this, I'm not sure you need a fitter.

But still, get your medical status checked out. If you've had a fall or done some especially heavy physical labor, you could need PT.

Another help for me has been to take an Iyengar yoga class. This style is strengthening, relaxing, improves your balance, and can truly be therapeutic. Certified instructors have some of that "yoga science" as to what positions tend to improve what parts of the body. I don't believe it cures anything by itself, but I do believe it's a part of feeling better, ailments or not.