Apologies for slow reply but very early in the week at work, we brew once only/week to create enough wash to keepa the stills running for at least 6 days. So quite clearly the P.C., God love it, is temporarily ignored.
Allan, Yes to fusels, esters and many more, volatiles etc. etc. all loosely called by some people congeners or congenerics - yes. You are most correct, however at the risk of starting WW3 from this site allow me to be so bold as to suggest that it is not the neutrality or lack of it that's giving you the headaches, it may be a quite serious case of dehydration.
Try this, next time you have a "session". FOR EVERY 50 ml of spirit at 40% alc/vol or equivalent, you drink (regardless of amount of ice, water or whatever added) 200 ml of water before AND another 200 ml after, also refrain from overeating eigh hours before, during, and eight hours after. Radical Stuff?? Well you may enjoy a "wee dram" instead of pain and suffering next day.
Now the next bit is as important as the water, as not only do they work in conjunction with each other, they also work independently. Take copius quantities of the Vitamin B Group, before, during and after the session.
Why I hear you cry???
1. Alcohol depletes vitamin B group
2. B group is a major metaboliser of carbohydrates, protein and fats.
3. Lack of B group, glocose to the brain.
4. B group helps maintain fluid levels.
Many people on this site will be very interested in your progress.
Many Regards - Brian