First (and this is the part others will agree with), it isn't that hard to justify continuing with the flushes, because it's normal for things to get worse before they get better. The standard answer here is "keep flushing!"
The junk stored in your liver is "out of circulation", not affecting things like your sinuses, until you flush it into and out of your bloodstream. What effects you before the flush is that the liver is congested, its processes hampered. That's one thing. After you flush the liver still isn't totally clean or healthy yet, and now you have MORE junk in your system, so that's two things. That's how I've come to understand it, anyway.
The second thing I wanted to say... and this is off the wall but I swear it is absolutely true for me. (And you said you wanted ANY input at all.) If I have sex, or more specifically, an orgasm, my allergies are worse the next day. Once I finally noticed this connection I found it to be undeniable: an orgasm today equals bad allergies tomorrow, including totally out of control allergies where I can't stop sneezing. Abstinence during allergy season helped me a lot.