If 5,000 IU and daily sun with shorts and short sleeves doesn’t do it I don’t want to know.
It’s more complicated.
Whether you are getting enough can only be determined by blood test.
No testing then you do not know.
Examples:
Some people do not convert sun exposure into vitamin D well.
People who have more body fat have less vitamin d circulating because it gets trapped.
The only way to know is to get tested.
I’d guess your level is low. Have you had your blood tested for vitamin D serum levels?