Weird rash on buttock (pic included)

[ThatDontImpressMeMuch90]

Sorry for the lovely photo of my rear end I'm sure it's exactly what people need to see on a Monday morning(!) but I was wondering would any wise Mnetters be able to hazard a guess as to what this raised rash is on my behind? Woke up yesterday morning with what appeared to be a spot but very itchy. Since then it's become itchier and slightly painful to touch. It's uncomfortable to lie on. Not warm or oozing. Haven't changed detergent/soap. Only thing is I started on nortriptyline a few days ago and I've heard of people getting rashes on it, but this seems a bit too localised to be a proper 'rash'. I know the wise thing to do would be to contact the GP but it's nearly impossible to get through at the moment, particularly on Mondays.

Insect bite that you have scratched and is now a bit irritated generally ? Or possibly hives .

It does look a but like an insect bite @SirVixofVixHall but haven't been outside the past few days. Yes I was thinking hives too, but can't think of any allergens. I know the nortriptyline may seem the obvious culprit but I would have expected that to be a bigger rash and on other parts of the body

My friend had a rash that started like that, similar looking, same place, itchy and it was shingles. Hard to tell at the moment and depends on how it develops.

Oh gosh, I hope it's not shingles @BuyDirt, I've heard that can be very painful. Thankfully there's no tingling/burning (yet) but will definitely keep an eye on it.

My money's on shingles