My hair??

So when I was younger I had waves/curls (idk if this is important or not) but when I got older my wavy hair went away (around 3rd grade) and now it's really frizzy and straight from the scalp and slightly wavy at the end. I dry brush my hair and when I take a shower my hair is wavy. Anyone know if my hair is straight but just frizzy (and if it is can someone tell me how to prevent it from getting frizzy) or if I should stop dry brushing it or anything.