What Is The Treatment For Severe Pain In The Joints And Muscles?

HI, I have been getting really bad aching in my joints and muscles around my midsection on the left side for approx 4 weeks. I am now finding that my left shoulder, leg and foot are really starting to ache. Is this just tension / stress or should i be concerned. I am currently 32 years of age and have no history of illness or injury. Thanks,