Thigh/hamstring pain while running

I have what feels like a perpetual pulled hamstring which hurts most all the time -- sitting, standing, running, etc. -- at the bone at the bottom of the left buttocks.  It's s dull persistent pain.  On top of that occasionally when I begin running I get a pain with each step starting in both buttocks and resonates down my legs.  It calms down somewhat during my 3-mile run.   Recently I've had another problem which I think is somehow related.  When I start my run most days, my front thighs hurt almost to the point of not being functional.  I have to gut through it for about a quarter mile at which point, though they still hurt, there is some relief. By the time I've completed my 3 miles I can still feel it but its very tolerable.  When I stop running everything is fine except i still have that pulled hamstring-like pain.  Any ideas?

[gymdandee]

Google Prolotherapy

[PAnnhibb]

Do you doing stretching before hand.  See if that will help.

[D_RUN]

Yes, 15 minutes stretching legs and back.