Benny, I have no real knowledge on this but I would go get it checked. I had very similar bruising on the inside of my forearm when I had completely torn my distal bicep tendon. I was able to finish the meet with minimal pain and didn't go to the doctor for nearly two weeks and was lucky they were able to get it repaired as the sooner after the injury they perform surgery the higher the success rate. The doctor will likely do an MRI and figure it out.
I know this isn't what you want to hear and hopefully it will turn out to be something minor but I would definitely get it checked soon.