Purpose in pain

What is the purpose of pain?
Is it only the body telling you something is wrong?
I know I'm alive because I'm in pain, yet that is of little consolation, for surely there are other ways to realise that.
Doctors, Drugstores and Drug Manufacturers all benefit from it, yet there must be another way for them to make a living at my expense.
It is universal yet personal, but better you have it than I.
Yes that is a selfish and self-centred attitude, and in retrospect I would not wish it on anyone, but why me? and what am I to do with it?