Hey I'm new at growing organic . And I got a little problem?

I'm 4 weeks in flower and over night one of my 4 plants started developing little red dots or rust spots all over upper fan leaves
Yes all organic amendments,
I use amendments as well, and I overfed with bottled organic nutes I thought I needed🤪 I was able to flush the soil but probably was build up from the nutes . And I flushed dried the soil quickly and flushed again then dried then water only so it took a few days ! But it brought the soil back to a usable state. I would say every situation is a experiment even for experienced growers . Personally I would try! What ya got to lose? Flush away and see what happens