Definitely try to find a way to check your runoff pH.
It's good you switched to tap water; distilled wter causes problems unless you are adding calmag to it. At this point, I would still add a bit of calmag to the feedings, and also slightly increase your nutrient strength. However if you find that your soil runoff pH is very acidic, you will need to flush well and bring it back up to 6.7 before proceeding.
A foliar feed of any commercial micronute supplement (GH Micro, AlgoFlash regenerateur, Spray-N-Grow, etc.) will help your plants green back up more quickly while you fix the problem.