Ok first of all breathe it is going to be all right we are here to help. Ok so if it has spread to other leaves and based on what I am seeing I would say yeah it is calmag, but don't worry it is not that bad. I am going to give you some remedies that I have seen take care of the dreaded calmag def.
1st. Change your rez, and I mean clean it good. I know this a pain but you have to start from the ground up in a sense.
2nd How close is your light to the canopy? If you can move it further away I would advise it.
3rd Here is a chart that shows what nutrients are available at what different pH's
View attachment 563495 one thing that a lot of people don't do but should (assuming you aren't using pH perfect nutes), is let your pH swing throughout the day, now this can be really tedious but when battling a calmag problem I will do anything to get it to stop. If you will notice basically where Calcium ends being readily available to the plant, that is where Magnesium begins being readily available. This is why I thing what a lot of folks refer to as a Calcium and Magnesium deficiency is really a Magnesium problem. So with all that being said I would if possible start your pH at like 5.6 and gradually swing it up to 6.1 or so maybe even 6.2. Now if you can't do due to time constraints or what have you, then I would suggest upping your pH slightly than you have it now like 6.0 or 6.1 then give the ole girl Epsom Salts or Calmag for a few days and see if that stops the problem. This is how I beat my deficiency last time.
Also I cannot overstate that your problem is not that bad and your plant is not doomed. We will get you through this, you see to me that is the challenging part of growing is that when you get thrown a curve ball how do you respond. It is one of the best feelings in the world for me to have a problem with a plant then go all super ninja on it and fix it. So try the remedy above and if that doesn't help we will continue to address the issue until it is fixed. I give you my word