question about lemon balm plant

by Karolina
(DC)

Hi!
I read your entry on growing the lemon balm plant and a few others, and everybody says how easy it is to grow.

I bought my plant 2 weeks ago and it looked totally healthy.

About a week into it, I noticed that something must be eating the leaves very fast (half a leaf of each leaf was missing on the entire plant)...they also had some black dots on them, not sure what it was.

Now there is hardly anything left of the plant.

It looks quite bad, and I can't find anywhere online anything on how to rescue it before it gets ruined totally.

I am a plant lover and I have quite a few in the room (I had my lemon balm in a pot too)...and all are relatively fine, so I am not sure what happened to this new one.

Can you please help? Thank you in advance!