Something wrong with teeth??

Since I got braces, a few months after (like 3 or more??) the white hard stuff started appearing, I brush my teeth to what it think is thoroughly and when I'm bothered i use those little brush thingy's the dentists give you and Im trying to start using the mouthwash daily as well but it's very hard and even if you try to 'scratch it of with a toothpick, it won't budge They're not necessarily big or noticeable but they are in between a few teeth and I'm getting worried if it's a permanent thing. I tried to take a picture but you can nit see it properly so there was no point