What's up with This Weird Symptom I'm Having?

Sooooo many things that could be going on that to even suggest something not only could be wrong, but could freak you out or calm you to something that needs to be addressed, that said the Doc will more than likely have an EMG done, it's where they have slight electrical currents run through certain areas to see how the nerves & muscles react, possibly an EKG to rule out anything going on with the heart, and an MRI to actually, 'look' @ the area. You may have damaged a nerve kickboxing even though you do this all the time that doesn't mean you are safe from injury! You can pull muscles just bending down to pick up a piece of paper! Just stay calm & get to the Doc ASAP & get checked out. Hoping all is well !

It sounds like carpel tunnel syndrome to me. It is a repetitive motion injury, so maybe take a break from the punching bag until you can see the doctor. Good luck!

Carpel tunnel syndrome comes to mind.
According to the Mayo Clinic:

"Numbness in hands is usually caused by irritation or compression of a branch of a nerve traveling to the arms, hands or fingers. Numbness in hands may be accompanied by tingling, burning, weakness or sometimes sharp pain.
If you experience hand numbness, consult with your doctor for diagnosis and treatment. In some cases, numbness in hands is associated with life-threatening diseases, such as a stroke. ".

When my wrists act up (I work with a keyboard all day so carpel tunnel occasionally flairs up for me), I wear a wrist brace for a few days and it gets better.
I've been told applying cold compresses help reduce swelling or internal tissue (there by relieving pressure on the nerves), but sometimes a little heat just feels a little better.

Since this is new for you, take it to your doctor just to make sure it's nothing more serious, and then see what he tells you to do about it.

You hit the bag just slightly wrong (no offense) and got a stinger. It'll subside in a day or so.

If you want to try and move it along, do some exercise/stretching with your arms.

I'd say it's coming from your spinal column, probably some vertebra near your neck.
Try some yoga stretches, downward facing dog comes to mind.

I have the same issue. The problem is in your back, not your arm. The muscles in your back around your shoulder blade have finally cut off the nerve that runs down your arm to your pinkie and the finger next to it.

I have the same issues and went to physical therapy for several months to get the nerve to move freely through my back and arm.

Get a hold of your doctor. He'll probably prescribe something to alleviate the symptoms and then therapy to get your back to loosen up.

I went to my chiropracter and told her I had pain in my right shoulder blade and the meat under my left thumb was tingling. She just nodded and said the right thumb tingling was the c4 and left shoulder blade was c5. She asked if I had ever had whiplash or any type of neck injury. Of course, I had. She said the injury had caused deterioration in my neck, causing the nerves to be constricted in the neck and irritated. After one adjustment I felt a lot better. I've only gone 3 times and I can tell a big differance.