It's a dull ache roughly in line with the bottom three fingers on the back of your hand, the pain of which slighty affects the strength of your pinching grip, right?
If this is so, the problem is plain and simple:
- You fist is not held tight.
- Your volume and intensity of training is too high for your level of conditioning.
Essentially, your stupidity fucked you. The solution is to stop being stupid with ballistic training. While certainly not uncommon, 2 minutes x 10 rounds is still a lot of heavy bag work. There are pros who don't work the bag half as much. There is other equipment and other ways to train which will give you benefit. Breaking up your routine will help conserve your hands. I suggest you get smarter and try it - at least until your hands stop bothering you so much.
But yes, see a doctor and get an X-ray to make sure your stupidity didn't end up breaking anything.