You can see the fluid through the ear drum. If it fills up too much , it can burst. Ya, hurts like hell. Especially with the TMJ at the same time.How do they diagnose fluid in the ear. It sounds pretty painful. I hope you can feel better on the antibiotic! My left ear had started to hurt..hurting a bit now. I'm still confused about my CT scan showing something and the MRI not. So is my dr. He says to bring it up to my Neuro. Come to find out, CT scans can show things in the mid ear that the MRI won't, and of course vise versa. Neither said fluid though.