Just wondering if you ever got any answers to your problems.
Treatment of constipation depends on its cause. In long term constipation, slowed bowel motility may be a problem. You might want to have stomach emptying test, which shows how fast your stomach is emptying,and also defecation test, which shows how muscles work during defecation.
Basic reasons for constipation in "healthy people" are:
1. not drinking enough
2. not enough fibers
3. not enough activity - physical or psychical, or anxiety
Disorders, causing constipation:
1. Lazy colon
2. Hypothyroidism
3. Adhesions or other causes of bowel obstruction
4. Megacolon e.g. from Hirschprung's disease - colonoscopy with biopsy is needed
Use your intuition, recall days where your digestion was regular - and what contributed to that. You may also have some basic blood tests done, to check for thyroxine levels and so.