My hibiscus is sick! Help!
I received this braided yellow hibiscus tree as a birthday gift one month ago, it was full and beautiful when I got it. It came from a green house that specialized in tropical plants. The first day the leaves started yellowing and falling off. I have it indoors as we've had frost over night in a west facing window which is very warm area (23-27 C). It has still flowered from the buds that were on there and only one bud has drop before flowering. I have sprayed it with Green Earth Insecticidal Soap 4 times and sprayed each leaf and stem and hand cleaned everything with a mix between alcohol, water and dish soap. I don't see any bugs but I don't know what else it could be. The leaves have little black dots on them (both the yellow ones and the green ones). Some of them turn brown at the edges and some of them curl up like they are burnt, not all do this though. Help! I want to save it but not infect my other house plants! What else can I do, and what on earth is it?
Thank you everyone!