Hello, and welcome.
From your description of his present symptoms, it sounds as if Cosmo may have vestibular syndrome. This is a condition where the vestibular system, which controls balance/equilibrium is disturbed by an ear infection or trauma to the head. Since you mentioned he had a fall, recently, a head trauma or concussion could also be the cause of his symptoms. The crusty stuff you saw coming out of his ears might have been dried blood. Here is more information about vestibular syndrome and head trauma:
Typically, vestibular syndrome will clear up on it's own, unless it is caused by an ear infection which would then require antibiotics to resolve the infection. However, this fall and his present symptoms, are of concern and if he sustained some head trauma, there's no doubt he should be evaluated in person by a vet for a full neurological examination, as soon as possible, so you can be given a definite diagnosis and treatment, if necessary.
If your vet doesn't have emergency weekend hours, bring Cosmo to the nearest ER vet center.
I hope all will be well with your furry boy!
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