Hi! I have about 12 tropical and exotic hibiscus plants in pots and I am having problems with 3 of them where the leaves have thickened and gotten kind of wavy. Some of the leaves have grayish spots and some yellowing.Some of the spots are "paper thin where you can almost see through it. One plant in particular has not put out any buds most of the summer despite fertilizing with Hidden Valley Hibisus Fertilizer. Can anyone tell me what this is? I have treated with neem oil and also with spinosad (some of my other plants I think have thrips, buds falling off) . Thanks for any help!