Ongoing pain in right thigh?

For at least the past few years, on and off every month or so i have had this pain on the top of my right thigh. It comes and goes every few minutes. It is extremely hard to describe, kind of like a squeezing, burning pain. Sometimes it has been so bad my partner has driven me to the hospital because i can barely walk, or else ive woken in the night with such bad pain i cant sleep. Doctors there diagnosed it simply as 'cramps' but i do not think this is correct? What the hell is it? Is it nerve problems? Muscle spazm maybe?