Whatever is wrong has been going on for some time.
I am leaning towards too much heat, not enough airflow, they look water starved and burned.
And I wouldn't be surprised if you have a bad infestation of either spidermites or root gnats.
Plus you really should have trimmed all that inner garbage out of there a long time ago, it's not going to produce much and is only using nutrients that it really needs.
And if you haven't stopped with the nutes stop now and flush with plain water.
And hope.