Hi, a picture would help but it sounds to me like something that my celeste had a few months ago. I'll post a picture of it later but the leaves on my tree developed black spots all over. Some said it's a fungus, some had no idea what it was. I cut the tree off at the base and discarded it, the root sprouted new leaves and is thriving now so I don't think it did any permanent damage . try an organic fungicide. good luck with it.

here's the celeste I had with spots.