Hi my battery health gets lower every day it gets lower 9 percent in 3 months what should i do?!

Hello,

Generally, Apple will replace the battery under warranty if the battery health falls before 80% during the first year.

See this for some charging tips by Lawrence Finch:

When to charge your iPhone or iPad

Good luck.

How long have you had it. The battery health number isn't a "real time" number. Sometimes it seems to hover around the same number for months, then updates. As long as the total number seems to be in line with the overall time you've used it and Apple's 500 full charge-discharge cycles to 80% battery health, it should be fine. Some do better and some do worse.