What Causes Heart Burns?

several months ago i had an endeoscopic test, tube down my throat, and the dr put me on an acid reducer , took that for 14 days, off for 14 then started again, until then i never had to much heart burn as i have now , do u think its the med i'm taking. i do drink to much coffee , half decaf half regu (light). it just seems that some days ok some not.