You have got me so curious!
When is the last time you used protein in your hair?
It does seem like your hair is incredibly porous. I started to think this when you said it was slurping up KCKT...and then GVP Balm...But then when you said it drank in mayo, eggs, etc. ...WOW. (It's hungry too!)
Even with a "Prell" wash, I cannot imagine non-porous hair being that absorbent. When is the last time you did a "floaty" test?
If your hair was coated with cones, I don't think it would be able to suck in all that stuff. I think your hair would feel sticky; not to mention phenomenally greasy.
Do you color your hair? (I can't remember what you said about this, sorry)
Did you have your hair analyzed very recently?
Could it possibly be your water stripping every last bit of moisture from your scalp? I moved to AZ from SoCAL last June, and the difference in the water is remarkable. Whenever I hear anyone in AZ complaining about the "hard" water, I know for sure they've never lived in LA. The water back there feels like rinsing with sand compared to the water here, and I don't have a water softener. At some point, could your hair have been absorbing too much water, and the heaviness led to trouble?