My 90 year old Dad occasionally suffers very badly from this, a hangover from his days as a miner. Very common among miners.
He struggles to treat it himself because of other injuries so I got to know this inside out, so to speak.
Firstly, and it's not widely known, Daktarin comes in two strengths. If standard struggling to get rid of it ask for the stronger one.
Secondly, miners swore by the use of surgical spirit for the worst cases. Undiluted on cotton wool swabs and wiped everywhere it itches and a bit further. Several times a day. Seems a bit vicious but it seems to work.
I accept no liability, do your own research, yada yada.