It’s probably coincidence, and I know it’s nothing at all to do with MS, but I’ve still got skin discolouration on my ankle from that road accident a year or two ago. Not only that, but it was occasionally weeping/seeping too.
Doc didn’t seem too worried - she thought the discolouration was from iron deposits in the skin following heavy bruising. I think she thought I was just being vain, so I explained I was more concerned about the weeping than the cosmetic effect. Hardly anyone ever sees my ankles anyway, as thanks to MS foot pain, trainers and lace-up walking boots are my last two wearable pairs of shoes - they can’t really be worn with anything but jeans.
So she said the skin may just be thinner and more permeable at that point, following trauma, and recommended I use moisturiser on it. I’ve been using bio oil, which is quite expensive, but she didn’t recommend a type, so I expect ordinary vaseline would have done just as well.
I’m only mentioning this, because I think hydrocortisone cream can thin the skin - so I wonder if it’s a skin-thinning issue, albeit with completely different causes to mine. Try paying it special attention with some moisturiser for a while, and see if it improves!