5th flowering week leaves discoloring

Well, for one thing, your PH is WAY too high for cannabis.... what your plants are exhibiting right now is a calcium deficiency. Calcium is absorbed by cannabis when the PH is between 6.2 and 7.0 ... but any PH over 6.5 is going to cause other nutrients and micronutrients to not be absorbed by the plant - so this is something you need to correct right now. I would do a hard flush to get the salts and built-up nutrients out of the soil and in the last gallon of your flush, put 1/2 strength nutes and 1/2 strength calmag. The damaged leaves will not recover but you can stop the deficiency from destroying your entire grow.. Wait until the soil dries out completely and then resume your normal water/feed/water/feed schedule - but always Always ALWAYS make certain that what you give her is PH balanced between 6.2 and 6.5 as you'll run into other problems if you don't. Good luck!