Battery Problem

The battery life has been decent but since the past 1 month if my phone gets under 15% the battery drains really quick. like from 15 to 15 percent in 10 min and then from 10% to 0% in 5 min. I don't know why that happens and not sure how to fix that. The battery itself is fine it holds long enough just the last 15% are really weird. Does somebody else face the same issue?