Please help with my tomato problem

Something has made my plant's leaves curl downward and yellow patches appear (see photos)this started around 10 days ago-can anyone identify the cause and possible cure please?

 

I wouldn't worry about the curling, I think it's pretty normal.
If the yellowing is only on the bottom leaves, it could be possibly a magnesium deficiency or just the leaves getting older.

If the plants are well looking in general, I wouldn't worry.