Help dandruff Hair problem ?

Hi everyone
im a 15 year old boy and i am trying to grow my hair. i have read up all about how to grow it long so i dont need help on that, my hair just covers my ear plus its thick and wavy. but the problem is i have dandruff. i have tried using t gel shampoo but i swear down it has stopped my hair growing plus it didn’t entirely get rid of it so because im trying to grow it i changed it to vo5 for a couple of months. it did grow but it made my hair even worse by making the dandruff problem bad and it felt like straw. is there any suggestions of shampoo ( not head and shoulders) i could use that will treat my dandruff problem and still keep it in good condition in order for me to grow it long. PS i dont use any styling spray or heating tools
thanks a lot 🙂