Yes Aguu, I would definitely get Mishka checked out and please don't feel bad, it could happen to anyone.
Whenever I have to bath my dog, Buddy, I stick some cotton balls in his ears, then when I have to water near the ear area, I hold my thumb on the cotton ball. It helps alot from him getting water in his ears.
I know it is much easier with a dog than a cat, but next time you have to bath Mishka, maybe you could try the cotton balls in the ears.

Keep us posted and how he is doing.

(((((HUGS))))) to you.