VITAMIN D PROBLEM pls help. D to rise?

Pls help me doctors ,pls,I have no one to answer my questions pls help. I had low VITAMIN D on May(3.9ng/ml) so doctor prescribed supplements which I took for 2 months, later in july I did blood test and VITAMIN D was 133ng/ml . So I stopped all supplements and didn't go under sun for VITAMIN d. I was having fortified vit d cow milk and home made curd. No other source of vitamin d after july . Yesterday (after 2 months) I did vit d test to check whether it has reduced, and my vit d was 158ng/ml, even more higher than previous test. I haven't taken a single supplement from july 20th Only milk and curd. How can my vit d increase without supplements?? I had taken a muscle pain killer (dolowin mr) 10 hrs before the vit d test, can that pain killer cause my vit d to rise?? Pls help me in name of humanity