Hi Joy,
Curling leaves can be caused by many things - thrips, mites and psyllids can be too small to see without, a 10X or greater magnification and they will be inside the curled portion. Fungi as you suggest but you need to wait for fruiting bodies to appear to get an ID to know what to treat with. In cultivation other things to consider are mineral toxicity or deficiency e.g. nitrates can cause distortion and curling in some plants. Also spray drift and chemical residues in the soil. Throwing chemicals at it without an ID is probably not going to help but if you can't identify the problem there's a good chance it will grow out of it.