colon and other abdominal cancers are always a concern with chronic abdominal pain. Many different tests look for these including a hemogram, different enzyme levels (e.g. liver function tests/lipase/amylase), and xrays such as cat scans and ultrasounds. It's worth asking your doctor if any of these would be helpful.
if menstrual periods cease, another concern would be adrenal & ovarian failure.
Whitish substance from stool can be mucous, or it can be lightening of the stool itself. If the stool returns to normal, that's reassuring. Persistently light stool makes one wonder about the ability for one to conjugate bilirubin, and needs to be checked out.