Heartburn definitely is a side effect of chemo but should pass within a week. And it's a particularly pervasive form of heartburn overpowering Tum's, Maalox, even Prilosec. Even the ultimate heartburn relief, baking soda in water drunk straight down, offered only the most temporary relief. What does seem to help some is anti-nausea medication because the two are related, even though for me the heartburn lasted longer than the nausea. If they didn't give you any to take home call your Doctor's office.
Chemotherapy is an ordeal, to say the least, but it can save your life. It takes a warrior's spirit to bear so keep fighting and know were all pulling for you.