My eggplant looks to be sick and its spreading to my other plants! I'm in Australia so its currently spring.
Does anyone know what it is? and how should i treat it?
It looks rather like a paint flick, does it not? Something like white latex primer from a large paintbrush. Notice how in the top image the leaf with lots of white on it has "sheltered" the leaf underneath to some extent. This indicates a wet mix falling onto the leaf, where an infection might be worse on the lower leaves in the shadow of the leaves above. You might examine the ground around your pots to see if any sign of white spots, also the soil surface. Spots should be readily visible on the red bark you have used as a mulch. Any amateur tradies working in the area?
Look very carefully at the leaf surface and try to determine whether the white is on the surface only, also underneath the leaf or inside the leaf. Also are you in an area affected by ash particulates in the air.