Sooty Aphids

As is often the case I can't do better than point you towards the RHS take on the problem of sooty mould, although like many others I find that spraying with a very dilute solution of washing up liquid or organic soap is quite effective at aphid control, although it could be that yours is caused by something else which is a bit more difficult to deal with.

Must say I've only ever seen sweet bay sold singly in pots, but whether you've got one or more than one to a pot they will certainly need repotting after 10 years.