I think there are different types of pain. For myself, I KNOW there are.
I think they overlap. The level of one type of pain can determine how much you feel another type. Like with your toe. If it hurts enough, it will take your mind off the other pain. If it hurts a little, you will notice the other pain more and vice versa.
If pain seems to increase when a new pain is added, it could just be that we aren't as accustomed to dealing with that type of pain.
But take it a step further. If one pain can "cover up" another pain, what if something else can cover up the pain? Personally, I play video games and it can cover up the thoughts of pain.