Your bloomage shows us a happy healthy plant. Has the problem been spreading? If not, it could be environmental such as weather, location, lighting, etc.... It is hard for me to see in the pic but is the color of the spots black, brown, or dark green? Do the lower leaves seem dry and shriveled, yellow and spotty, or feel oozy when you rub them? Was it like that when you got it or has it developed since you took it in? Honestly though if I were to hazard a guess based simply on appearance I would say it looks like chemical burn caused by the growing nurseries pesticide application. Typically this leaves some unsightly spotting but otherwise doesn't kill the plant.