Thanks for the help guys, I ended up using some crushed up aspirin in water to reduce the redness, I did realize that it was probably due to irritation. I find that if I use a 5 blade it irritates my skin, I always find fewer blades better for my skin which is why I shave my face with a DE safety razor. I shaved my head again last night and applied a little more olive oil as a preshave and things went smoothly, I got a really close shave and no irritation on the back of my neck after a few hours. I am glad it was not any remaining issues from dandruff and hopefully that will not come back.
Also I would like to at some point try to attempt an ATG shave on my head so I can get the true baby but smoothness on my scalp, how long should I wait/how many shaves would you all recommend so I do not end up with lots and lots of irritation due to my skin not being tough enough.