Beginner Gardening: Hibiscus Issue: yellowing leaves with spots, 2 by SavvyDaze

SavvyDaze wrote:
This Hibiscus has been troubling since I bought it back in June and I can't figure out what is wrong with it. I am hoping someone here might have an idea. I have some good, lush, really dark green leaves and then a really ugly section with yellowing leaves marked by what looks like dark green spots, but appear more blackish or brownish on the backs of the leaves. Any ideas? I really want to save this little guy cause the 1 flower he did produce this summer was a beauty! (Pic 3)

Thanks!