I agree on the calmag issue. It's underfed. The distorted leaves are a good sign of that with the speckling and rust spots. IMO it's missing lots, and MC alone will not fix it, so I'd stay at 5g/gal for a feeding or two and add 5mL of calmag along with it. Then bump up to 6g of MC with no calmag.
No more SC.
No more SC.