Personally I would use the clay internally, I don't think putting it in the ear for infection would be a good idea. And, to apply it on the outside is a mess indeed. A little head flapping and clay all over the walls, furniture, etc!
My dog gets it everyday in her supper bowl. I liquefy it. Make sure it is not thick and sticky. Mixed in with her dog food, last nights supper and if needed a bit of canned food and liquefied clay. No problems. Start with just a little bit to get them used to it and then go from there.
I would think that clay internally and MMS drops would make a good combination. As CO2 suggested use MMS with the HCL activator and you could probably also give it internally at the same time.