Im just starting growing a couple weeks ago, so dont take me as an expert on this. just educated guesses
that spec on the leaf? ignore that, think of it like a freckle or a blemish, doesnt look like its going to get worse(you dont see the rest of the leaf losing colour so it looks contrained to that one spot)
How much light is it getting? it could probably use a bit more to get it really going. Unless its getting lots already.
But... whats that white stuff on the stem?