What Causes Pain In The Thigh?

i have a very sharp and severe pulsating pain in my upper right thigh which comes and goes , the pain lasts for 3-4 secs and is painfull enough to take my breath away it feels like a form of cramp but a lot more painfull almost a stabbing but pulsating pain it started 3 days ago only happened 4 times in half an hour but again last nite in bed