My sales have dipped too. But not to zero sales, just a 50% fall in sales as an affiliate.
Like others have said in other threads it could be due to seasonal factors.
Think about it... most people would be saving for their vacation in December. Also, they would rather purchase physical products for Xmas or even the New Years.
Health and weight loss niche products would definitely dip too as people have the mentality of procrastinating it to next year as part of their 'new year resolution'.