Lump at the back of wrist?

It's definitely not gangloid cyst. I injured the front of my wrist about 2 months ago and my hand was pushed backwards. It was a really strange sensation l. It felt like the tendons in my arm collapsed. It.stopped hurting after a while that last month this lump showed up. I've had my exams in the last few weeks so I've been in agony while writing. I've been meaning to go to the doctors but haven't had time since I also work. Right now my whole arm aches and my wrist is just throbbing. What could it be???