Medication Issues

I saw my doctor last week and explained how I'd be fine during the day with the medication except I'd flare up at night time. He suggested taking the Nexium later in the day, which I've been doing for a week now. I haven't made any new dietary changes (just keeping with the ones I've already made that were working), but now I seem to be in pain all the time. I don't know if it's because of simply taking the medication at a different time or not. My doctor did tell me that he'll keep me from having an endoscopy as long as possible. I have two months of medication. Should I go back and tell him it's not working or wait and see if it's the time change or what?

I'm currently on 40 mg of Nexium. I guess pain all the time is more of an exaggeration. There's definitely more times of pain than no pain, and even then, there's still some pain, enough to be noticeable. I know I should call the doctor but I'm wondering if changing the time the medication is taken causing something.