This is an interesting question. You are certainly not an isolated case.
The "origin" of foot odor has been examined in many studies.
This study conducted by Marshall et al focused on the microflora
found on normal feet (no foot odor) and compared it to feet with foot
odor. They reported a higher population densities of staphylococci and
aerobic coryneform ...
Usually flu's are accompanied by fevers, when your internal thermostat is effectively 'reset' by the virus and your body temperature increases. When you're recovering, your internal thermostat is now resetting to its correct temperature so your body cools down. The way you cool down is by sweating.
As for your question regarding detoxification, the kidney ...