Sorry, can't tell from description, really needs a pic, but I'd guess the plant got too cold. Brown spots aren't usually from too little light. That would usually be growth too leggy or too pale a green.

Photo added. Im really hoping someone can help me save this poor plant. Good news is it's not getting any worse...

Sotto....the blemishes look brown. When a plant gets frostbite, spots are gray and soft.
By chance, were leaves gray first before browning?

If spots are brown and crispy, the problem could be lack of water or humidity...Toni