CA125 - Normal level?

I recently had numerous tests done after having weight loss, groin pain radiating to my hip, and slightly swollen lymph nodes in my groin.  All my tests (CBC, protein, CA125, CT Scan, endoscopy, colonoscopy, vaginal ultrasound with doppler follow through) have come back "normal".  My symptoms have stabilized except for intermittent pain in my right groin and hip.

My 1st question is related to my CA125 level.  It is 18.5.  I know this falls within the "normal" category of 35 and below.  However, I read two articles that suggested that anything above 15 should be followed up on within a year.  One of the articles suggested that within a populating of 400 heathly (no known health concerns) women of all ages a CA125 of 18 was at the 95% level.  Should I insist on a follow up?

My 2nd question is why I have this pain.  I feel it almost daily and does not seem to be cyclical.  It is tolerable but is always on my mind.  It sometimes feels as if it is right at the hip bone.  Could it be arthritic?  It does not seem to be affected by activity although I don't seem to feel it at night - it does not keep me awake.

I amd 38yrs old and have had 3 normal pregnancies.  The last was 18 months ago.