My sister has being feeling a burning feelibg in her chest and stomach has being feeling bigger what symtoms would that be?

The differential...: ...diagnosis is VERY different if your sister is 4 days old versus 40 years old. You have also told us nothing about her clinical circumstances, medications, acuity of onset, nor severity of distress. We're going to need a little help from you to be helpful to her please.

GERD/gastritis?: Assuming your sister is also young but older than 18, have her try over-the-counter Prilosec (omeprazole) or similar PPI's. If after several days no improvement, see your doctor.