Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry that your pup seems uncomfortable and has been shaking his head and twitching his after his walk tonight.
This is usually due to an ear infection or itchy ears.
Even if his ear canal looks normal the ear canal is "L" shaped, so it is possible to have an infection in the deeper part of the ear canal that you cannot see due to the sharp bend in the canal.
Or it may be that he has an inner ear infection causing pressure and discomfort.
Or he may have suffered an insect bite or sting that is making him uncomfortable
Any one of those scenarios would make sense that Wyatt is shaking his head.
I do think your pup needs to see his veterinarian if this continues, but I don't necessarily think that it's an emergency.
In the meantime while you are waiting to have him examined there are some things that we can do to help him feel more comfortable.
Since most ear infections are secondary to allergies and the inflammation they cause and head shaking can be from an allergic reaction too, you can use a combination of antihistamines and high doses of omega-3 fatty acids to help. In combination fatty acids and antihistamines work synergistically, much better than either one alone.
You can give:
1)Benadryl (diphenhydramine only don't use the combination products with decongestants or acetaminophen as they can be toxic) at a dose of 1mg to 2mg per pound of body weight or one 25mg capsule per 15 to 25 pounds of body weight orally every 8 hours.
2)Claritin (loratidine) at a dose of 5mg per 25 pounds of body weight once or twice daily.
3)Hydroxyzine at a dose of 1mg per pound of body weight orally every 8 hours.
4) Chlorpheniramine at a dose of 4mg to 8mg per dog once or twice daily.
5) Zyrtec (Cetirizine hydrochloride) at a dose of 1/2 mg per pound of body weight orally every 24 hours. That would be one 10mg tablet per 20 pounds of body weight. Make sure it is NOT the formulation with a decongestant (such as Zyrtec-D) because dogs cannot tolerate decongestants.
Some dogs do better on one antihistamine rather than another. Give the one you pick a week trial and if it isn't working try another. Be aware that antihistamines can cause sleepiness or hyperactivity in some dogs. These side effects do wear off with repeated use.
Omega-3 fatty acids are fish oil products. 3V by DVM or Derm Caps ES are good brand name products. Use the high end of the dosing schedule for your pup's weight. I recommend an omega 3 fatty acid dose based upon the EPA portion (eicosapentanoic acid) of the supplement as if we do that the rest of the supplement will be properly balanced. Give him 20mg of EPA per pound of body weight per day. For example an 18 pound dog could take 360mg of EPA per day.
I also recommend using a gentle ear cleaner like Oticlens daily now to try to remove as much of any waxy debris as possible. This removes excess wax and keeps the ear pH at levels that discourage infections. When the ear is sore many dogs won't let you squirt things in their ear but if you soak a cotton ball with the cleaner, then place it at the top of the ear canal opening and massage the ear from the outside, putting pressure on the soaked cotton ball, the cleaner will be instilled easily. Wipe out excess cleaner and waxy debris with dry cotton balls. It sounds like he already let you clean his ears with Zymox otic, so that's good.
If this is infection related once you have his infection treated and cleared use the cleaner twice a week as that helps prevent infections and also allows you to know what a normal ear looks like and catch ear infections very early. Sometimes with an early infection simply cleaning the ear daily is enough to stop it in its tracks.
If this continues he will need to see his veterinarian. Do not clean his ear the day of his veterinary appointment so they can gather a sample of wax for testing.
Best of luck with your pup, please let me know if you have any further questions.