Are you taking anything for it? Allegra, Zrytec, other antihistamine drug? You can try Sarna lotion, although it's clearly a systemic problem and the cream will be very temporary and might not even work. I find that it does give me some relief, although it doesn't last longer than a moment. I just keep applying it, so I don't scratch too much. I've also woke up with blood all over my sheets, so I know I'm scratching at night. With the Zrytec, I notice I do sleep a little better, but in the morning I'm really groggy and don't get moving easy. I also take Zantec, a GERD medication, but it's an H2 Histomine blocker, so it helps with itching. I take that 2 times a day, along with Allegra twice a day and Zrytec at bed time. I'm also on 5mg of prednisone, but even with all these drugs for my rash and itch, it still bothers me, just not as much. If I miss a dose, take it later or to early in the morning, I'm bothered more at night, so I take it late morning and at bedtime, so the morning dose helps keep me from itching throughout the day and into the evening and the bed time dose keeps me asleep and not itching too much. I notice that I start to itch more around the time I take the morning dose, at 11:00.
Have you had the rash biopsied? It should be, so talk to your hematologist about getting a biopsy, or just make an appointment with a dermatologist who can biopsy it. You need to find out if it's a lupus rash, hives, or other autoimmune rash. Although, getting it biopsied might not confirm anything and you'll still have no clue, but if it's vasculitis or lupus, you'll need treatment to knock it back, because vasculitis in the skin can mean you might have vasculitis in other organs. Lupus rash that first appears, or gets worse, could mean lupus flare and possible internal organ lupus attack.
Creams won't do much, because it's systemic...pick up some over the counter Allegra and Zrytec and see if that helps. The combination of drugs I have now is about the only thing that gave me a little relief. I know there are other drugs the immunologist talked about trying if I don't get relief from these drugs. There are some immune suppressant drugs and he also said Plaquenil would help, which is why I went back on Plaquenil. If you're on Plaquneil, maybe a dose increase for a while. He suggested 400-600 daily for me. I started back on 400.
Good luck tomorrow...I know how you feel, itching is the worse, anxiety provoking when you can't scratch. I can't scratch my legs, because I have chronic clots and my legs swell, so when I scratch, I end up with infections and I think that has made my problem worse, because I'm always fighting a bacteria that gets under the skin when it breaks from scratching. This might be what's happening with you too. Each time you break the skin, you're introducing bacteria, which your body has to fight off and with autoimmune disease, your body over reacts. It's a vicious circle that needs to be broke.