Sickly cactus

Hi. My cactus was doing well up until about about a month ago. It now has quite a few light brown areas. I wonder what I can do to restore it to its previous green health. Please see my photos.…

Opuntia Cactus*

I grew this opuntia cactus from a seed of a cactus pear which I ate.  It is about 5 years old.  Growing indoors in a condominium apartment facing east.  It has never been taken outside.  Recently it has started having…