It seems to have few problems: possibly overwatered, and also a pests or a disease.

Rocks at the bottom do not help, you need drainage hole(s) if there are none. Mix a lot of sifted/rinsed perlite with the soil - minimum 50/50% or up to 70% of perlite. That would make a better draining mix. If rot got too far througout the plant, it may not be possible to save it. BUT I am not sure how much it is there.

If there are bugs, you need to treat them.