Confused

I randomly started testing for Ovulation Monday because I'm never regular and had a misscarriage mid May.  It was positive so I started thinking about it and took a pregnancy test and got a VERY faint positive.  Today I switched brands and I don't see any faint positive at all...anyone had hthis happen?  First was a pink dye and the one I did today was blue.  Digital on Monday was BFN but I wasn't surprised since it would probably be early if I was pregnant.