Suggest Treatment For Severe Pain In The Hamstring

Hi been getting this sudden sharp pain, deep in my left ham string. For 2 days now on and off. When it comes only last a couple of seconds, but its so sharp and painful, I want to scream. This is a familiar pain. I remember first feeling this pain about spring time this year, while riding in a military vehicle for a couple hours. My second encounter was in a vehicle again few weeks later, then this last time was yesterday, just sitting in the living room. And finally this morning laying in bed.