i have a couple tilties that do this but the infection is long gone and they are still clear. serraphim hates it when her ears are touched and will shake her head everytime i touch them. chancey will do the same thing if i've been patting his head, brushing over his ears, long enough; eyes if i've been rubbing the base of her ear by her chin. its only been the tilties that i have noticed this with and only after they became tilties in eyes' case...
now there is definitely something wrong with serraphim given that she is presenting other symptoms now and she was the one most prone to head shaking. but it would be odd that all of them would have the same illness at varying degrees at the same time... and chancey and eyes are not losing weight like serraphim is. serraphim has had the perma tilt the longest out of the three but i still don't think her current condition is related to that.
i never really thought much about the head shaking. in fact, i didn't even recognize the connection of head shaking and the tilties until this topic got me thinking about head shaking in my own rats. i never thought of it as a connection to an illness, it just never occurred to me. but given that all three of my tilties will shake their head when their ears are messed with (with varying degrees of sensitivity) it leads me to believe that there might be something connected to the fact that they have a perma tilt. perhaps after the ear infection their ears are more sensitive to touch? maybe, where they had to deal with an ear infection for the length of time that they did they no longer like their ears being messed with...? this is certainly food for thought.
so, i guess my question to you is if your rat has had an ear infection in the past that he was treated for? if he has been, does he have a perma tilt as a result?
of course, it may not be related for your rat at all and so like jorats asked, does he have any other symptoms? even if it is just as simple as a minor behavior change