Is it potbound? Turn it out and check the rootball, if its all solid roots, then it needs a bigger pot.

Hi Zappa like Bamboo said they could be pot bound , but as for feeding I have two plus an olive tree in pots and I feed them with a seaweed fertiliser which seems to work, Roy.

I. Have a bay tree in a large pot which appeared to be suffering a couple of years ago. I watered it with my home made comfrey 'juice' and it recovered. But if it is pot bound it will need re-potting.