This is one of the most uncomfortable aspects of PD and autonomic nervous system dysfunction and a chronic problem. Through much trial and error I have come up with a plan that works for me - and makes things better overall (not perfect, but better).
1) Miralax (polyethlene glycol) 17 gm nightly (gentle and can be used long term) The key is regular use
2) Align probiotic daily
3) Omeprazole 20 - 40 mg daily for GERD
4) Smoothie daily with: 1 cup coconut milk, 1 cup yogurt, 1 cup frozen fruit and greens, 1 tbsp peanut butter. Mix thoroughly to break down the frozen fruit/greens - keeps the bloating controlled by doing the digestion for you. Serves as a meal for me daily or every other day.
Vitamix blender works great.
5) Drinking at least 4 to 5 eight oz glasses of water daily.
6) Stay active - no couch potato - just get up and move.
7) Smooth Move Senna Tea 1 to 2 bags per cup if all else fails.
Be careful with strong laxatives - they can deplete your intravascular fluid volume and lead to problems maintaining your BP (orthostatic hypotension).
Hope you feel better.