Hypersensitivity means that the same health problem hurts more the longer the problem persists, and is usually the reason why chronic pain patients can fall into a negative spiral.
Technically, a doctor can describe this way better than I can, but I usually explain it this way:
Imagine that you hit your knee against a sharp corner.
Imagine that you hit the exact same spot on another sharp corner the next day. What happens? IT HURTS MORE.
Now imagine that you (accidentally) hit the exact same spot on your knee against a sharp corner every single day for three months.
After just a few days even a very mild touch will hurt really bad, and after a week or two, just the sensory signal of fabric brushing against your knee is going to hurt like h%&$.
That's what living with chronic pain is like.
I imagine that the nerves are like network cables in my body. And when a certain cable has been jampacked with signals over a period of time, lets say it's been highly trafficked because I've had a lot of pain in a specific area, the brain increases the bandwith, i.e installs broadband instead of a 56 k modem connection...or ... it builds an eight lane highway, where there used to be a little dirt track through the jungle...
So, your brain and your nerves are exaggerating the pain signal, tricking you to make it feel alot more painful than it needs to be. Good thing we can trick them too.
The easiest way to do that is by stroking the skin, because the sensory signals from the skin travel by a different nerve system than the pain signals, there's some sort of "gate" into the brain which means that while the skin is being touched, the nerves want to transmit those signals to the brain, and so there
is less bandwidth left over for the pain signals!!! So simple, yet so effective.
(Btw... my physiotherapist described this in a much better way... I'm sure there are smarter explanations out there)
Anyway. It works. Try it :)
Or even better, have a loved one do it for you.
Choose a part of your body that has little or no pain, yet is quite sensitive, like the inside of your underarm maybe? You have to stroke it gently for a while before the "gate" is closed for the pain signals, and it doesn't shut out everything, but maybe 60%. Which is just about as good as many prescription drugs out there... no drugs, yet less pain = win/win :).