I don't see anything obviously wrong with your camera settings (i.e, Exposure Compensation, Metering Mode, or some other setting that might be causing it).
So, it's more likely a hardware issue.
Try resetting your camera settings back to factory defaults anyway.
You'll find a RESET
menu choice in your camera's menus designed for that purpose.
Also, try a known good, freshly charged set of batteries. Sometimes, a defective battery can cause incorrect voltage resulting in strange symptoms. Make sure you don't have a bit of oxidation built up on the battery contacts, too (I'd use a pencil eraser, a q-tip with a touch of alcohol, or specialized contact cleaner that won't harm plastic and make sure it's dry if you use alcohol (store bought alcohol has a high water content and isn't ideal for this purpose).
If those suggestions don't help, you probably have a component failure of some type (sensor, or supporting chipset).