With pics phosphorous def, Roots choking, nute burn? Im lost on my plant.

I am trying my first indoor grow, using the lollipopping method and super cropping. I've only done 2 small grows outside (3 to 6 plants). I didn't use nutrients on my outdoor grows at all and am now just learning how important they are for indoors. 2 of my plants are fine, few yellow spots from lack of nutes I believe but majority green, nothing like this one. They are about 4 weeks into flowering, and they have all been given the same ratio of water/nutes and are on a 12/12 timer. This plant is has brittle yellowing leaves with brown and black spots that are very brittle. I trimmed some of the leaves because the tips were completely dead. My timer has glitched a couple times, like today it was on for 18 hours and I didn't know because i was at work, so i didnt know if i have stressed it? I have read through about 100 posts but can't seem to narrow it down. I have read it may be my roots choking each other, nute deficiency/overload, over watering, or Phosphorous def. I want to narrow it down asap since I only have three plants. I just started feeding them a miracle grow 10 60 10 for until thurs when i get paid to get better nutes. I was told blood meal is good for my scenario. I water them twice a day about 40 ounces of water a piece. The cabinet temp doesn't go over 78, and this is a CFL grow (650watts). Please let me know if you need more information +rep to anyone that can direct me to my problem.

I posted pics of the top of the plant, the roots and bottom leaves. It has only seemed to effect the lower leaves tho. Thank you all!

Obviously rootbound, get the plants into something bigger for those roots to spread into.
The spots of death look like calcium deficiency, also the minor interveinal yellowing is the beginning of magnesium deficiency, so cal/mag should help for both.
Bigger pot + Cal/Mag

root bound. low on nitrogen. low on other micro nutes cal/mag probably.

retransplant into bigger pots, buy some fertilizers.

Do you suggest any nutes? Possibly that I could get at lowes, home depot or walmart? Only one grow store near me and its a bit of a drive but I will if necessary.