Sharp pain slowing me down

Hi I am looking for some advice When I am running I get a sharp pain between my shoulder blades, it seems to creep in after 4-5 miles and only gets worse the longer I run. By the end of the run I can hardly move my head back or to the sidem my head feels rigid on my neck because its too painful to move it. I have tried consciously relaxing my neck, shoulders and back but it doesn't seem to help. I stretch before and after my runs, so I'm not quite sure what else I can do. Any help or advice is appreciated Thank you

A sharp pain IMO should make you stop rather than slow you down ... get to a Dr and get it checked

could be signs of a heart attack http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/signs.html

get to a doctor pretty soon and get it checked

Thanks for the replies, but I think I may have given the wrong impression of the pain I am experiencing.

It's more the muscle tightening in between my shoulder blades, like its contracting with tension. I did mention it to one of my customers that ran and he suggested opening my hands while running rather than making fists, but I run with my hands open so I kind of discounted his advice.

When I say it slows me down I mean I tend to concentrate more on the pain rather than enjoying the run and being able to up the pace should I feel like it, I don't mean it slows me down against all my efforts

It almost certainly sounds like you are holding your hands, arms or shoulders too tensely either when you run or at some other time.  I used to get similar problems when I was going through a stressful patch with work.  I was too tense all of the time, but it only really manafested itself when I ran.

Take a look at how you sit in the car - do you really grip the steering wheel or are you relaxed?  Also how you sit at a computer, when in meetings, when talking to people, whan watching tv etc.

If the muscles are already tired and over worked then running might just be the final straw.

You may benefit from some upper body strtetches and strengthening exercises.  Also a massage might alleviate the problem in the short term so that you can work on putting a more permanent solution in place without so much discomfort

Could also be general bad posture and slouching due to weak upper back muscles.