Hello Marybenson5,
I understand you would like some help figuring out why your battery health has decreased so much in the 6 months you’ve had it. I'm happy to assist you with this.
As you'll see in the following support article, it's normal for your battery health to decrease over time as it chemically ages: iPhone Battery and Performance. However, the decrease you're experiencing does seem a bit excessive compared to what is typically seen with iPhone batteries. I recommend backing up your iPhone and restoring it to factory settings next. After you restore it, set it up as new without loading your backup and see what your battery health shows. Here are links to the steps you will need:
Once you've tested it out, you can then restore all of your data from your backup: Restore your iPhone, iPad, or iPod touch from a backup. If you continue to experience the same thing, reach out to Apple Support next: Contact Apple Support.
Thanks for using Apple Support Communities.
Take care.