My heart shaped Hoya is turning brown at the bottom and it seems to be spreading! It used to be bright green then it turned pale and sickly and now it looks as though it is dying! My boyfriend bought it a year ago in a little red pot and we have it on the window where there is bright but indirect sunlight. The only reason why I think it might be dying is that my boyfriend watered it a week after I watered it but he said the soil was dry. How can I revive it? Is it too late??