This is most assuredly a calcium deficiency... But it's also looking like you've got a twin problem of nitrogen toxicity... Once of the reasons we'd like to see diaries is to take a look at what you're feeding the plants and in what amount... what your PH is, what amount of water it's taking every day, what the temps are, etc... it all helps us help you...
You're getting so close to harvest it may not matter but if this were MY grow, I'd cut back on any grow nutes you might be giving them (grow nutes are particularly high in nitrogen) and I would add a dose of calmag to my nutes - and make sure your PH is between 6.0 and 6.2... that way, the calcium you'd be giving it will be happily absorbed by the plant...
Good luck!