If it is sulphur problem check the pH of the soil, and lower it if needed. the leaves i think will gradually get more pale. It is easier for the plant to take up sulphar at a lower pH levels. Logically I would suspect that animal products would be the ones that contain sulphates. Maybe this is where bat guanao comes in? not sure of that tho. Citric acid also would prob do same thing. bound to be some experts here that know the best things for that.
did u add calcium? that makes this problem it seems, maybe tap water with high calcium levels even tho the ph is ok??
with the nitrogen, again animal shit basically would work well, in theory lol . manure, or that blood meal? Is it organic soil? that where nitrogen probs are more common, lots of tree bark n stuff