Nutrient lock-out? Rootbound?

After doing some researching on my plant, this fear hit me out of no where, I don't know if it's irrational or not. Anyhow, my sativa dominant girl is just over 4 feet tall and growing fast as hell. I recently just added nutes a few days ago and due to some changes to my site, I had to go back a few times within a short amount of time. So the day I went there I added nutes and she looked great just an hour after the watering. I come back the next day and she looked like nutrient lock-out, almost like iron deficiency, yellowing on random scattered leaves. I've just read mixing nutrients is a very good way to create nutrient lockout because of a chemical reaction. I mixed Schultz plant food plus and traces of miracle grow rose blossoms and watered my girl and it looked bad the next day. Today she looked alright but I doused her in 3 gallons of water to help flush her a little.

Another question that's making me worried. The issue of root bound...
I know sativas very fast and mine being over 4 feet tall and not even flowering yet. I'm afraid she will root bound in the 7 gallon flexible tub... I need to know if it's best I transplant her when I get paid tomorrow before she buds, but after the nutrient issue is fixed.

Advice please?
+rep

This was today's pictures. Looking better but in person, you can really see it better because my crap quality phone doesn't show it in detail all that well.

any feedback please?