Bay Leaf spots

Can anyone identify these black spots on the underside of my bay leaf plant
and if it is a fungus how should i treat it.
They appear mainly on the underside and very little on top of the leaves.
Under a magnifying glass it appears like some sort of fungus.
About 50 percent of the leaves are covered with these spots.

 

It may be a fungus, but just wondering if it is a result of insect attack last year, aphids maybe.
which leave behind a sticky substance and then fungus grows on it.

Just a suggestion.

 

Hi,
Thanks for your answer, i looked for a fungicide for edible plants but there doesn't appear to be one, i will try removing the affected leaves to stop it from spreading, and use an organic insecticide.