Pain is percieved by the brain as electrical signals from an injured area of the body. Different symptom types indicate what kind of injury or problem is causing that certain type of pain. The type of pain that I have experienced within the last few years was inflammatory pain.
Inflammatory pain is caused by damage to specific tissues or tumor cells.
One day, on one of my many trips to the gym to perform one of my daily exercise routines, my shoulder had felt a little bit funny. I hopped onto the bench press, warmed up properly and continued to lift my weights. On my 3rd set of my exercise, I was working with an easy weight that I could handle often. I had a terrible pain in the back portion of my left shoulder, put the weight back and went home. I tore my rotator cuff! Ouch! It was less then a 30% tear, so they didn't perform any surgery, I just had to deal with the pain for a few days, but my shoulder was quite puffy and red for a days, not to mention I couldn't move it. That was due to the inflammation cause in the joint. The rotator cuff is made up of 4 muscles that help perform exercises in which your shoulder rotates and presses upward. It's actually one of the most common injuries in my line of work (personal trainer). If one of those muscles has a weakness, it can cause a tear in the area. It felt like a dull burn for a few days and I could not lift my arm, due to the swelling. Luckily , it went back to normal and with a little rehabilitation, the shoulder is as good as new!