What Causes A Heartburn Like Pain And Dizziness?

i have heartburn like pain (heaviness or full sensation) when i lay down and when i do activities like washing walls, windows etc.using upper body and doing bending down while doing these activities also sometimes i feel dizzy during these activities and also dizzy when i first lay down. weird weird. i am 63 years old and i am not on any medication whatsoever. ibuprofen for occasional pain and tyenol or ibuprofen pm for sleeping.