It sometimes takes the scalp a few weeks to get use to the BS wash, and you also may have had a buiild up of dead skin which is now being exfoliated. It will be fine soon....To help with the dandruff, or even any scalp itch, always finish off with a cold head rinse, as cold as you can take. This helps and feels refreshing.
The ratio for sea salt is 3 1/2 tbsp to 5 cups of water, you can mix this with the BS if you want, you can use it as a spray on your hair (try not to get the scalp since you have dandruff), or you can pour it on your wet head. What ever method you use, always rinse it out by the two hour mark or it will dry out your hair. The sea salt mixture is a dread accelerator....
While you have the dandruff, get that in order first, then start using the sea salt if you want. Don't worry, you will get it all fixed up. Once the BS exfoliates everything on your scalp and it adjusts to the change of using it, you scalp will balance out. Make sure to always follow up with the ACV rinse after using BS, the ACV balances back the PH levels in your hair and keeps dreads soft.....peace