To me it appears to be nute burn, I would get a ph test kit if you can (pet store, fish aisle, ph test kit with drops, not strips).

Flush with ph neutral water, I assume your pot has good drainage, test your run off to see if ph is ok (I believe 6.8 is good for soil).

Organic soil will have enough nutrients for first few weeks.

Do a lot of searching on this site eventually you will start to think to yourself, I read that before,
when that happens your usually onto good info, start by checking this out:
Cannabis FAQs / FAQ , Recipes, Medical Marijuana


Good luck :thumbsup: