It looks to me like its been over nuted. You should not have to add nutes to such a young plant until it uses up that which is already in the soil mix.
I do not start adding nutes until a couple of weeks befor I am ready to 'flip' the plants into 12/12.
If I were you I would consider 1 of 2 cures.
1) repot into fresh soil mix
2) flush with ph'd water

Just my opinion.