I’m new... idk what to do

Soooo… I got a few clones from a dispensary in the spring, 3 different strains. This is my first year growing my own and sadly I can not create optimum conditions for my ladies.
That being said I’ve been growing them in 5g buckets and they have been doing great!
All getting nice and big then my pet pig ate one… tragic day it was!
So down to 2 plants and they were doing great but now are getting sad. The one is having a ph issue which I’m in the midst ov dealing with but my other one has gotten a spot near the bottom ov the stem that has gotten super yellow and the branches that were growing in that area wilted away.
I’m worried that by the end ov the outdoor season I will have lost the whole plant if I can’t figure out the issue. Any tips would be great!
Sorry for poor sentence and paragraph structuring. Lol
Thanks in advance!

Pictures help. Sounds like your root mass may have overtaken pot or they may just be underfed.

Ok here’s a pic ov the spot