ovarian cancer screening

I am a 33 year old with two children.  Two years ago I took about 4 cycles of clomid.  Since then every cycle around ovulation time I experience pain in my lower stomach.  Sometimes it even hurts to sit down hard.  It feels like all my ovaries and uterous are swollen and sore.  This usually lasted 3 days or so until after ovuation.  It seems to be getting worse now, with the soreness sometimes continuing after ovuation until my period starts.  Usually  during my period and a few days afterward I am pain free.  I have always assumed that it is just ovulation related pain, and I have been told by a doctor that I have several big follicles growing each month.  1.Is this something that should be checked out right away?  2.What other symptoms do I need to be aware of for ovarian cancer?  
3.If the pain comes and goes can I assume that it is not cancer?  

Thank you.