What is wrong with it am using cal mag with feed

Most likely you applied a wrong ratio of nutrients mixing a & b. 98% of a plants nutrients uptake from soil solution once applied. An incomplete fertilizer solution can lead to an imbalanced pH, as the specific nutrients included or excluded can alter the solution's pH. Ph is the balance/ratio of differently charged atoms. Your job is to provide a balanced diet. Can't just give her 90% nitrogen and hope for the best. Go buy NPK Raw Grow, half tspoon per gallon. Easy.

Still a seedling, very sensitive until she reaches veg (4-5 internodes) because she has so little stems she cannot store very much so she is far more reliant on everything she needs to grow being readily available. Don't use calmag if your tap water is already got enough calcium, apply every 2nd or 3rd week or as needed. Most important things she will need until flower is nitrogen and phosphorus. Biggest detriment to those two nutrients will be maintaining correct ph and ec, as soon as any environmental factor becomes compromised such as ph, overwatering or underwatering both these nutrients just stop working as they should in a medium and will become skewed. She is currently presenting a need for nitrogen but why when you know you fertilized? Then something must be making it usable to do so or making it harder for some reason.

Looks like a bit too much feed rather than a deficiency. At that size, the plant doesn’t need much CalMag + full feed might be too strong already. I’d suggest giving just pH’d water for a few days, then resume with ¼–½ strength nutrients. She’ll bounce back fast

growdiaries.com/grow-questions/88416-2-week-old my answer

Which kind of feed? How old is the plant? Which kind of sustrate, and if soil, do you use light mix or a mix with more nutrients? To check whats maybe wrong, it would help, if you send more informations. By my first assesment I would say the plant needs more nitrogen.