Sudden, severe cramping in waves at the onset of menstruation. i became very weak and pale, knees buckled and near passing out. another ectopic?

Preg test : If you were having an ectopic pregnancy then your pregnancy test would be positive. Take one now. If negative consider birth control to help decrease the painful periods.

Possible: A second ectopic pregnancy is more likely if you had an ectopic pregnancy previously. Sounds like you need a pregnancy test. There are other possible reasons for severe cramps at the onset of menstruation, but an ectopic pregnancy can even be life-threatening. If you're still having severe pain, get a pregnancy test.