Nute Burn?

Hi All,
This is my first grow and first time posting here. I could really use your help!
I just started having a problem with a couple of my plants. They are about 3-4 weeks old. They were living in 1.5Q containers and were starting to suck up water much more quickly. They would go through a full drench in a couple of days. When I came back from a long weekend, they were looking pretty yellow on the bottom leaves and I thought it was a nitrogen deficiency problem. A few days beforehand I had watered them with a dilute Miracle Grow Plant Food solution, about 1/3 the recommended strength, which I thought would be ok and not overpowering. They had been growing pretty quickly the last few days as well, before this problem occurred.
I turned them upside down to check the roots and they had reached the bottom and were circling around. I transplanted them yesterday into 3-gallon pots using Garden Pro potting soil, dehydrated manure and hummus, and perlite, with a sand base for drainage, plus some Espoma organic fertilizer 1:25.
The pics of three plants are attached, the first two are of the one that seems to have it the worst. The last two are of different plants. Please help!?

flush them 3 gallons of water to 1 gallon of soil

Flush them with what the other gentleman suggested. Flush with 2-3 times the amount that your container contains. You could also use a solution thats called Clearex. It is used for schedulled leaching of soil and also for pre harvest.

thanks for the advice folks! i flushed the first plant 2x and the 2nd two plants 1x, since i recall the first got a bit extra nutes before.

how long does it take for the burn symptoms to disappear?