Sudden chest pain after years of PPIs

Very worried, been on lanzoprazole (2 x 15mg) for years and suddenly 6 weeks ago it felt like I'd stopped taking the medication. I'm very diligent with the tablets, always taken correctly. Diet has been bland for years. I can't really see anything different, now constant niggling pain, significantly worsened after meals. Currently double dosing PPI, plus Cimetidine at night, plus Gavison, bed elevated, etc. and still need more gaviscon in middle of the night. No real improvement in 4 weeks. Anyone experienced anything like this?

Thanks SharonZ, Eating habits have changed a bit simply because of Covid but I think my diet is as bland as ever. Not really any stress, but obviously a lot of change in the world for a while, which I don't find particularly troublesome. I had an endoscopy twenty years ago (following a trial with zero lansoprazole to check if it was really needed. I was in agony very quickly) An urgent endoscopy is being done this Wednesday.

It's been diagnosed as a sliding hiatus hernia. Still not sure why suddenly so much pain while already on PPIs (and now double-dose PPIs). Overall, I'm relieved, it could have been much worse. Waiting for H Pylori results, and I think Celiac, before further call with consultant in two weeks.

Negative on H.Pylori, double dose PPIs worked in the end, combined with elevated bed, multiple small meals, and gaviscon before bed. Now trying to reduce lansoprazole back to single dose, which for me is 2 x 15mg daily. Still no idea why there was a sudden increase in pain while on the normal dose, but all moving in the right direction now.