I am typically a top performer and a hard worker, but my seasonal hay fever is making life (work) hell.
Besides sniffling, which irritates some of my colleagues, I often get drowsy from medication and otherwise my eyes are itchy and I find it difficult to breathe.
This makes it hard to concentrate, and I have noticed that in the past few weeks I have received more admonishing by my manager for not doing a good job; I feel helpless, especially because I never underperform and I always understand, but this time - for some reason - I find it hard to follow what he wants from me / or what he doesn't want me to do - unless something goes wrong and then he tells me that's what I wasn't supposed to do.
Our work involves a lot of figuring out things on our own.
I don't know whether the drowziness/irritation is causing me to be in "automatic mode" rather than "learn/listen/think", but most certainly I am finding it very hard to absorb new information and apply it at work or think on my own feet.
Most of the time I am just doing routine and hoping to go home early every day. (Whereas my work involves a fair amount of non-routine, independent thinking type of work, and in fact for most of my "good years" I was able to figure out things on my own). Generally I it's as if my active mind is "switched off" due to this illness.
What I am most concerned about is that my manager repeatedly told me "This is what you were supposed to do earlier" and I find myself confused and lost.
What should I do in this situation?
UPDATE: Many answers and comments here assume that I might be able to put the cause of the problem (the allergy / its symptoms) under control. I am 100% sure that my current state is as best as I can get, at least for the time being. Reasons include the range of medications I can use due to adverse effects interacting with other conditions I have + other commitments which means I must stay here and at this job. So, given these constraints, how could I deal with the issue? What if my allergy cannot be controlled the season? How can I ensure I don't loose the job?