Hi Louis43,
Welcome to Labforums, and of course welcome to your chocolate Lab Louis!
Sorry to hear about his ear problems, probably the best advice i could give you would be to go back to your vets, or maybe get a second opinion. If the problem has been going on a little while, and doesn't clear up with antibiotics - it's puzzling what the underlying cause is. There is some useful info on this link:
http://www.labradorforums.co.uk/ears.html
Maybe someone else can advise you further, i hope you get some answers soon...
You could also try posting on our sister website,
www.vetpro.co.uk where your post will be answered by veterinary staff.
Keep us posted, all the best to yourself and Louis,
Julie