Felt gassy and mildly constipated for two weeks. took a dose of miralax once and had a very good bowel movement. cleaned out. should i keep taking it? feel totally fine now. how does it work so well?!

Depends: Constipation/gas is normally due to changes in diet. If you lack fiber, vegetables, exercise and 8 glasses of water a day you are more prone to constipation. You could be hypothyroid but that is unusual cause for constipation. Most pharmacies carry different drugs to treat constipation which you can pick out yourself. No particular reason Miralax worked so well.