Taking domperidone, Nexium (esomeprazole) appx 8months getting severe pain knees/hips at nite 2-4 times per week also have hiatal hernia is meds causing this?

Malabsorption? Those medicines could be causing you to have a malabsorption problem where the stomach is not absorbing the nutrients and minerals that it is supposed to. Check out "why stomach acid is good for you" by dr. Jonathan wright. Things like zinc, vit b12, and others may be deficient in you causing your muscles to ache.
Package insert. Check the package insert for the medication, and look at the section on adverse reactions. You could also check with your pharmacist, or go to epocrates and download this on your smart phone or check it out on the computer. Hope you feel better soon.