Positive test

I took a clear blue about a week ago almost two. I waited about 5 mins and it came out negative so I threw it in the drawer and went on with my life. A couple days later I got my period. I went to the Doctor a few days later and took a pee test there. It was negative. Today I went in my drawer and looked at the test and it's postive. You can see the plus sign clear. Is it possible for a test to turn positive cuz it sat for awhile? I don't see how I could be pregnant if I got my period.