Looks like spider mites to me, Check under the leafs for spider webs, Use a magnifying glass because they are VERY hard to spot with the naked eye, If you see little black things crawling or webs, I would get "Don't Bug me" Its a solution you spray on them, and After a week depending on the infestation it should go back to normal, again this is IF you have spider mites, I would also probably check the PH, Hard to tell with only pictures. But good luck hope you find out what the problem is.
- W n L.