Spilled an oil based concentrate on aggregate driveway. Had 3 companies come out with no success.
First Attempt: cleaned, resealed. Was fine for 5 months until a major freeze/snow. A whiteish area appeared after the freeze in the exact spot.
Second Attempt: cleaned and etched with what I believe was muriatic acid. They left a circular spot and seemed to try and reseal with the wrong colored sealer (see picture)
Decided to attempt to strip the sealer myself, degrease, and reseal but making slow progress and feel a little lost/overwhelmed. 
Last photo is where I am at currently.
My question is what is the best way to move forward to ensure the spot doesn’t resurface?
My plan currently is to etch and degrease the area I’ve already stripped but I am worried I will not be able to match the color over the whole driveway. I am think I need to do 2 coats of grey sealer over the stripped area and then 1 coat over the entire driveway but I am unsure.
Below is where I am at currently after stripping the area
