I have suffered intermittently with a rash in my groin that appears to be a combination of fungal and psoriasis (perhaps inverse psoriasis).
I have used daktacort amongst other things, but have never found anything that actually made it worse.
The best thing to clear it up quickly I found was an ointment called Triderm. I used to get this when I worked outside UK and I think at one time it was available here, I forget now.
The replacement in UK is called Trimovate. I also use a steroid called Elecon.
If I get an outbreak in my groin, it very quickly (24 hours or so) becomes raw and painful. I find a very sparing use of elecon plus trimovate for about 5 days clears it. I continue the trimovate for another 2 or 3 days, and an standard antifungal for a further 5 days or so (eg daktacort or daktarin).
Trimovate is a mixture of a steroid, an anti-fungal and an antibiotic (as was Triderm).
There was a difficulty to obtain it last year, it was temporarily off the NHS list. My Doctor was able to prescribe it, but chemists had to order it for me, and some refused.
My Doctor also prescribed me some Timodine and Elecon to tide me over until the Trimovate could be supplied. He warned me that I might need to phone around to find a pharmacy that could provide it.
He was willing to prescribe the Trimovate based on my history and the fact that Trimovate was clearly so effective in my case.
My local Lloyds pharmacy (I called in on the way home from the doctor) said they would not provide Trimovate, and in fact tried to say that my GP was not ALLOWED to prescribe it. They even tried to confiscate and keep the physical prescription.
However, I understood the NHS regulations and told them that they did not know what they were talking about, I insisted that they return the prescription to me and I left.
I phoned a local boots who had no Trimovate in stock, but they checked with the main store in the city and they confirmed that they did have.
I went there. But they did insist on phoning the GP surgery to confirm the prescription, and it was going to cost more than usual and it was "off the NHS list". The Practice manager confirmed. Boots were able to give me one tube and ordered the second tube, which arrived 2 days later.
In my case, I suspect that a fungal element seems to trigger the rash and the psoriasis.
I now use a medicated anti-fungal powder after every shower, to dust my groin. I dry my groin and genital area with paper-towel (kitchen roll) to avoid any fungal contamination of my towel (I do the same for my feet and toes).
I have reduced the incidence of these outbreaks in my groin from about 1 every 5 or 6 weeks to 1 every 6-8 months, and Trimovate knocks it dead.
You cannot buy trimovate, but maybe your GP will prescribe one tube to try.