I am sorry to hear that Satchmo is scratching his ear madly, this may mean that he has an ear infection or an allergic reaction to something.
Another cause for excessive scratching can be an ear mass/tumor.
Of course the ideal situation is to see his veterinarian and have his ear examined and the debris tested to see what sort of infection he has to get him on the right medication, but I understand that may not be possible for several days with the Holiday weekend.
In the meantime 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 you can use a combination of antihistamines and high doses of omega-3 fatty acids to help with those. In combination fatty acids and antihistamines work synergistically, much better than either one alone.
You can try:
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 or one half of a 25mg capsule per 8 to 15 pounds of body weight orally every 8 hours. Benadryl is very bitter and some cats will drool excessively or may even vomit because of that. That doesn't mean it is making him ill, he just hates the taste. If that's the case with her try a different antihistamine.
OR 2)Claritin (loratidine) at 1/2 of a 5mg per 12 pounds of body weight once or twice daily.
OR 3)Hydroxyzine at 1mg per pound of body weight orally every 8 hours.
OR 4) Chlorpheniramine at 4mg to 8mg per dog once or twice daily.
OR 5) Zyrtec (Cetirizine hydrochloride) at 1/2 mg per pound of body weight orally every 24 hours. That would be one half of a 10mg tablet per 10 pounds of body weight. Make sure it is NOT the formulation with a decongestant (such as Zyrtec-D) because cats cannot tolerate decongestants.
Some cats 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 kitties. 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 his 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 8 pound kitty could take 160mg of EPA per day.
I also recommend using a gentle ear cleaner like Oticlens daily now to remove as much of the waxy debris as possible. This removes excess wax and keeps the ear pH at levels that discourage infections. When the ear is sore many cats 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 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.
Once you have her 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 his ear skin surface is very red after cleaning you can apply a light coat of cortisone cream (like cortaid) to the ear skin with a cotton ball.
Do not clean his ear the day of his veterinary appointment so they can gather a sample of the wax for testing.
If he won't stop scratching his ear you will need to place an elizabethan collar (cone of shame, lampshade collar) on his so he dosen't damage his ear.
Best of luck with your fellow, please let me know if you have any further questions.