You can always post a picture to your profile page.
But it is really hard even then to tell what something is through a picture on the internet. You've had this checked out by your doctor? A bump on the wrist like that can be carpel tunnel syndrome or as your doctors said, tendonitis. What did they direct you toward for treatment if they go with a diagnosis of tendonitis?
Okay, wow. I totally see that bump! Your doctor wants to ignore that? Now, I have gotten some bumps on my hand near a finger joint. It went away. But it looked different than that. After seeing it, what about a ganglion cyst? https://www.mayoclinic.org/diseases-conditions/ganglion-cyst/symptoms-causes/syc-20351156
Looks similar to me. Tell me what you think.
Hello~I just looked at the picture, I hope by now it has cleared up, but if not, I suggest seeing a chiropractor, you could have some dislocations in your wrists, this could be causing the inflammation as the area is being irritated. The chiropractor will take an x-ray of the area and then discuss the results with you, he/she will probably adjust your upper back but pay more attention to your wrist, they can give the wrist small adjustments and they really do make a difference.