If i get constipated for a few days would it be better to take ex lax or miralax (polyethylene glycol)? no bulk forming laxatives those back me up even worse

Either: You can take either - they both work well. However, my experience with patients in the hospital is that Miralax (polyethylene glycol) works faster and gentler.

Miralax (polyethylene glycol): eat more fruit,more fibers. hydrate well and exercise. eat prune,and drink juices. you can place half the bottle of miralax (polyethylene glycol) in 64 oz of Gatorade, and drink it in 12 hours, after you take four tablets of dulcolax in the evening, and another four in the morning, and start drinking. this is how they clean the colon for endoscopy. then start fresh by eating the right food,hydrate,fibers,prune,juices.