Do Whitening Strips leave spots on your teeth?

I used the Walmart brand of whitening strips a while back, but a few days after I started, I stopped using them because when I took them off, I would see bright white splotches on my top front teeth. They would eventually fade, but I didn't want to make them worse. Ever since then, when I get up in the morning and look in the mirror, I often see the white spots reappear, which can fade all the way out within an hour, or they will only fade some I can notice it throughout the day somewhat. I am about to get married but my teeth look kind of yellow from being a southerner and always drinking that sweet tea! I've heard all sorts of good things about Crest White-strips, but will they make the splotches worse? I kind of umed they showed up in the first place because of the low quality strips I was using, If they even were low quality? Should I try to Whitestrips or proffesional whitening? I sure don't want to make the occasional white spots worse!