Hello &
I'm sorry to hear you are having such a horrible time of it & as a migraineur who's had both ovaries removed I sympathise with how dreadful you're feeling.
There are quite a few members who sadly have to deal with migraine so you may find it helpful to enter migraine into the search box have a look at past threads on the condition. Mary G is very knowledgeable & if you post on a thread on which she's contributed in the past she may be reading & see you need advice. You will not be able to send her a PM until you've made 10 posts, I think, but after that you could maybe approach her that way.
I'm not sure from your post whether the combined Evorel Conti is the only type of patch you've tried to date but if so, wondering whether you might want to ask your GP to change your HRT from gel to oestrogen-only patch, to see whether that method reduces, or better still eliminates your migraines. Some of us find that hormone fluctuations can make migraine much worse at this stage of our lives & you may achieve steadier levels of oestrogen via patches, though there is no guarantee as there are still fluctuations over the life of each patch. If you are still in peri, your own hormones will likely be adding to the ups & downs, though as you say you were on conti HRT before the Mirena fitting I wonder whether you are now postmenopause?
The itching sounds as though it could be a problem with histamine, assuming you don't think this simply due to the very dry skin many of us experience at menopause. Again there are past threads on histamine intolerance if you want to search for these. If you like I can look up links I've posted previously that may be helpful.
If your GP is not helpful, could you change to another or as CLKD suggests, perhaps go to a specialist menopause clinic? If there is no NHS clinic nearby or a long wait & you are in a position to go private, Newson Health have been helpful to many women on here. If not near you, I believe they are offering teleconsults & you could maybe ask for a cancellation to be seen sooner.
I'm sure others will be along soon to say hello & offer advice.
Wx