My 2 1/2 month old has flaky skin

So my son still has really flaky skin and scaly skin and his pediatrician said it’s cradle cap and it can spread and told me to wash hair with dandruff shampoo twice a week and put cortisone cream on skin where it’s scaly and rough and it hasn’t worked yet. He is still super flaky and scaly and i just am at my wits end. It’s all over his whole body like this. PLEASE anyone have you dealt with this and if you have what had worked for your babies? It will look like the scaliness goes away after bathing and moisturizing but then it comes back within hours 😭.