looks like nute burn. needs nitrogen.
calmag.and more nutirent. should solve it
No offense but it its burn why would he add more? That would end up probably killing his plants.
Do you have a pH tester? It would help because those symptoms could be pH flux, overnute, or even phosphor def. Thats the tricky part of growing, the lookalike problems.
If you have no tester you should flush the fuck outta your medium several times, and let them go to see if it stops. If it does stop it was nuteburn. If it continues its either pH or phosphor def. But then again if your adding
cal-mag (which I'm pretty sure is another word for Lime), then that should be balancing out the pH so I'd look into the phosphor def.
Have you changed nutes since veg? Whenever I don't change nutes for 12/12 I get the same symptoms at the same time which shows me to use more Phosphor.
Good luck and keep us updated.