Strange Tests

I took these tests throughout 4 days and it started out faint and then got clearer. I’ve taken other brand of tests and all negative. The first two I got at the pharmacy, the last two I bought at Walmart so they were different brands and I still got these faint lines within the first minute. Yesterday I tested using two of the same tests which showed very faint lines and another test that was negative. I tested this morning and negative. I got a positive opk on the 6th I had intense cramping on the 11th which was strange to me which is why I started testing. The app has me at 3w 4dys so I should be seeing something on all tests by now. What could this mean?