I Have Had What Feels Like A "glob" Of Something

I have had what feels like a "glob" of something in my throat everytime I swallow. Also, sometimes with pain, a lot of burping and regurtitation. This has been going on for a month. My Dr. ordered an ultra sound as he thought it may be gall stones and wanted to check my gall bladder. That test came back perfectly normal. He put me on Omeprazole twice daily for 2 weeks instead of once daily. I still have the same symptoms. I have been on Omeprazole for 20 Plus years and wonder if maybe it is not working anymore?? Thank you for any help you may have, Lenette S. Selle