battery expanding??

Hello, my phone is shutting off randomly when there is plenty of battery. When i charge it and it comes back on, it reads 100% battery life. Also, when it is 100% it can drain down to <10% in a matter of minutes with no apps running. i did recently get a battery replacement under the apple cost savings program at the end of 2018 ( the deal was due to the newer iOS draining the battery life to fast). I just went to the local AT&T store to pick their brain and immediately she noticed the side of the screen being forced away from the metal casing and told me to contact Apple immediately as this is a sign of the battery expanding. Please help.