Growing outward but not upward??? No new height

Hi everybody,
I'm trying to figure out what is wrong with this plant. I got two clones at the same time, and have treated them the same way - they're in organic soil, with 18/6 light. They had been outside but they weren't doing well so I moved them inside with a light.

One of them has been doing quite nicely now - at least, I think so. The tall one looks okay, right? The last one - nothing looks unhealthy? (This is my first grow!!)

The other one is acting very oddly (first 3 pics). For a long while it had virtually no new growth. It finally started sprouting some new leaves, but it hasn't really gotten any taller - so now the new leaves are tiny and are really getting packed in there, and there hasn't been stem growth to accommodate it. Does this look familiar to anybody? What do I need to do to fix this?

Thanks!

i think when you have a nute burn or a nutriend def. your grwoth stops..in pic one i saw some brown leaves maybe you should fix that and then start seeing the plant grow
if its possible r/o water at ph6.3 (you shouuuld really try to put your mind on PH as i think its one of the most important thing to grow 'green' weed)
since i adjust my water to a ph of 6.3 i could over feed the plant a bit and nothing happens ..