Foliar feeding can be bad because you want your plants to feed from the roots, also it can invite mold and sun/light burning. It's not all bad, I bet you can recover. Raise your lights. If you put your hand under the light at plant level, you don't want it to be very hot. Do you have any ventilation? Also MG soil is too hot for mj, unless your really really really careful. I would not feed and flush flush flush with 6ph water no nutes. There are also solutions that release salt buildups better than strait ph'd water, like florakleen.
Good luck and JJJJJJJAAAAAAAAHHHHHHHHHH!