Take your light to 24" - 30" .. only move closer if you observe stretch.. you'll eventually move to 20-24" in short order i bet with those lights.
seeds are good for 2 weeks, so if you have fed, stop doign that for now. Give ph-only with runoff and wiat for top layer to dry before irrigating again.
soil has nutes too, so it could be a bit hot.. could be pH .. could be lack of watering with evaporaiton. etc etc.. so, consider recent behaviour and eliminate the least likely ones. Take it easy on plants, and they'll recover shortly.. .probably around the time you begin feeding, i bet.. but let it play out and let plant tell you want to do.
