Could constant nausea and a burning in your chest be caused my over-dosing on anti acids and heartburn pills?

Doubtful. Antacids and heartburn pills tend to help nausea and chest burning rather than cause it. More likely is the scenario that your underlying problem that is causing the nausea and heartburn is not under good control. You probably need to see your doctor or a gastroenterologist to optimize that treatment regimen. Good luck.