I Have Had Reflux For Many Years. Have Been Taking

I have had reflux for many years. Have been taking 1 Omeprazole each morning and that has controlled it well. About 4 months ago I also started taking a probiotic.
One month ago we moved and I stopped taking both. About 3 weeks ago I stared feeling nauseous and light headed. I took the Omepeprazole and it didn't help - felt like it got worse so I stopped. The nausea comes on when I am getting close to meal time. Like today at around noon it became pretty severe. Nausea and light headedness. I ate but it took a good hour before I was feeling better. Still am not 100%. I am 71 years old and active I had 4 stents put in my right coronary artery 14 years ago. I have no chest pain, no muscle pain, no heaviness in my chest.

what could this be?