Go to a pet shop and get some ear cleaning solution,, few drops into the ear and then gentley massage the ear you will hear it squelching a bit.. after a few minutes a cotton wool ball wipe the inside you will probably see a bit of gunk.. if your dog is shaking its head alot and hasnt stopped after a few days take to vet as could be something in the ear.. hope that helps
If your dog is shaking it's head, it may have a mite. Usually pet shops sell ear cleaning kits. We take ours to the vets. It might cost a little more but we feel it is worth the pro job. If that is not an option then a few drops of solution and then a gentle wipe can help.
Use a mixture of 50% malt vinegar and 50% filtered water using a makeup remover pad thingy - do it weekly as a preventitive - rather than playing catchup, which invariably means an expensive vet visit.
Got this from a Basset breeder - American Bloodhound but with no legs - and they are the pits when it comes to ear infections