In my experience mixing neem with fert: the burn problems seem to have a tendency to increase.
What I might do next watering (if your still in the first three weeks of flowering)
foliar spray with RO water, then fert, then Ro only on bottom stem part, then light neem oil dilution on same bottom stime part ( mean light baby), then Ro on stem/
I don't mix meem with fert. the above may seem a pain (it is) I have a lot of spray bottles (large scale would need 2 gal. + sprayers).
I get my plants somewhat immume to pests with occasional sprays of neem (always alot lighter than directions, less than half, and only two drops of Dr. Bonner's Magic Peppermint Soap per liter) during the first months of life.
neem after flowering seems to freak them out a bit (observation only no science lab tests yet).
The neem oil may act as a magnifiyer and increase nitrogen use.
Peace love and Dead Mats With neem.