Hello mate, sorry to hear that. You need to provide more information and some pictures.
What's your grow medium, how often do you water, do you feed your plants with full recommended dose or half, if you are able to take EC or PPM readings of your nutrient solution and from collected run-off, that would be ideal. Also some info about you set up, lights, temp, humidity, would help.
If you are using calcium carbonate powder as your calcium additive, you more likely intoxicating your plants with this stuff, it also brings pH to alkalinity level.