I still think that would be too much N for a flowering plant M8 especially with all of the issues you have been having. This is what I would do....
Yes put it into 12/12. Flush the shit out of it first to get rid of any and all build up of salts etc from the ph/nute issues. go to your hydroponics store or anywhere you can buy "foxfarms tiger bloom" nutes. They will know what you want. the NPK of that is 2-8-4 with micro nutes and minerals in it. That is perfect and has worked wonders for my grows. After you flush your plant, put 1/2 of teh recommended amount in with a gallon of water, add 1/4 teaspoon of superthrive ( you can get it at wal mart Home depot or any gardening shops). Before you water your plant with it, get a ph water tester kit including the ph up and ph down solution form your hydropinic stores (they are everywhere) and run a drop test with your water. Since you have flushed your medium until the water coming out the bottom is clear, you should not have any more issues as long as you follow the steps above. Always know the ph of your water and nuted water before applying. That is what really matters. After the first feeding, go up in strength gradually to the recommended amount. I use 1.25-1.5 tsps of tiger bloom per gallon of water... I hope this makes sense.... good luck