15 ys diarrhea, constipation, abd pain, interstitial cystits, connective tissue dis dysautonomia. Lactose intol. Would u advise I try gluten free diet?

If celiac sprue. Try to find out the underlying problem in your gut. Can test for celiac disease with blood tests, confirmed with biopsy. Gluten free diet reduces carbohydrates as well (decreased grain intake), so symptom relief may be related to that, not gluten.
Worth trying. Worth trying a gluten free diet for at least 6 months to see. Gluten damaged gut takes 6 months minimum to heal.