If you were to spend a moment thinking about a time when you were unfortunate to have an accident i.e. a trip or fall, cut yourself while chopping vegetables, sprain a muscle, etc. what happens? You would probably feel an immediate pain which would then be followed by the longer lasting dull ache until it goes away.
Our perception of pain can sometimes be affected by what we are doing at the time. For instance, a footballer who is so engrossed in his game may take many blows to his body but because his heightened state, any painful signals which would normally be sent to the brain are temporarily canceled out until the game has finished and he starts to calm down then suddenly the pain signals start their journey. For more about the process of how pain works look at Gate Control Theory by Ronald Melzack and Patrick Wall.
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