Forgive Growladyeastmidlands... I think she sees hermies in her sleep!
Your diary doesn't tell us about the pH and I think this is probably the most critial thing to look at here... It also doesn't tell us what nutes you're giving and in what amounts... another critical piece of information missing... If you think this is a calcium issue (and obviously you do since you stress you're giving calmag and extra calcium), you need to know there are several causes of that which won't simply be fixed by dumping calmag into her.... one is a nitrogen lockout... if you have a nitrogen toxicity, that will prevent the plant from absorbing nutrients like calcium... but I don't know what you're feeding and in what amount - plants in flower need a lot less nitrogen than plants in veg...
The other cause is a pH that is out of range... pH needs to be maintained between 6.0 and 6.5 for the plant to have access to the calcium being provided... If it's possible that you have a nitrogen toxicity, you will have to flush your plants with 3x the pot volume of pH'd water, let her dry and then give her 1/2 strength nutes for the first feed cutting back even more on any nitrogen rich nutes... if it's a pH problem, you need to get that fixed before the plant can uptake the calcium.
I happen to think the problem isn't calcium but phosphorus - but the same thing that I've described above works here.. you just will need to fix any nitrogen toxicity and/or fix the pH and then give her good bloom nutes and a PK boost of some sort... most nute lines will offer this.
Good luck...