fert burn for sure,causing a nute lockout, beginning to show magnesium def.

your problem is the soil with the ferts pre mixed in it,

flush once with water & 1/2 tabelspoon per gal of epsom salts(epsom for the mag def)

flush 3 times the volume of the plant container....1 gal pot = 3 gal flush

after flushing use a small amount of the epsom flush water to foliar feed (spray leaves)....transplant immediately (soil with NO FERTS MIXED) or this issue will continue to plague you.

do not water for atleast 1 week or till you see signs of leaves drooping