Need nute ihfo, ph numbers.
I use Dyna-Gro also and never had a problem.That 20 day plant shouldn't be having problems this early so its kinda strange.It looks like cal def but this usually doesn't happen until later on.The only thing I do is add some extra cal/mag because the amount in there nutes is a little on the light side.I also have my PH at 6.4 or 6.5 so you may want to lower yours a bit.
Yes,follow the 5ml chart.I raised the dose when mine hit 5 weeks and they seemed to like it.