I'm currently growing a few chilli plants from seed in my apartment, but the largest one is having some problems. Some of the leaves are curling, whilst others have a dusty, salty substance on the bottom and light green patches on the top. Parts of the stem have started to brown. (Photo gallery here: http://imgur.com/a/IPvEI)
As I'm really new to growing plants in general, I have no idea of the cause - I've been watering them fairly frequently recently (around once a day/once every two days) as they live in a sunny windowsill (well, for the UK) and the soil appears dry. None of the plants it lives alongside (also chilli plants) are having the same issues, though it is the largest of the plants and may possibly require repotting? I've spent a long while Googling, but haven't been able to find anything that matches the exact symptoms.