looks like several things in the works here...do you ph water..have you fed nutes...i can see in that pic the starts of cal/mag starting to get locked an burnt leaf tips...so imo you didn't ph check water an nutes an you overnuted an have cause a lock-up on the roots...i suggest letting the medium dry a lil then flushing with ph'd water then water normal for a week then start nutes back a 1/2 dose...all checking ph....peace az