Hi Annemarie,
Interesting that you were born and lived in the Chicago area! I've been through New Mexico, and it's beautiful. If I lived there, I would miss the four seasons, but right now avoiding winter sounds like bliss! 
I, too have had bouts of simply maddening itching, maybe once every few years, but not on a permanent basis, thank Heaven. It's the kind that no matter how much I scratch, it never "reaches" the itch, and in fact, makes it worse. It can last for months, but I don't generally have any visible evidence of the problem...not the rashes you describe or any redness, or anything.
I've only found two things that help my itching when it occurs and that is to never, ever start scratching, as it only inflames and escalates the sensation, and Solarcaine spray (made for sunburns) as it contains a topical anaesthetic.
I'm currently on Enbrel, and it has worked for me for many years...maybe twelve or thirteen. I've never even heard of Xeljanz.
So what are you taking now? I probably mentioned it before, but when I first had this lymph swelling, I immediately stopped taking both the Enbrel and the methotrexate, and the resulting pain was beyond excruciating. I hope you're not dealing with that now. 
Do you have a lot of joint deformity? My hands and feet are (I suppose not surprisingly) the worst.
I'm asking a lot of questions here...I hope you don't mind. Do you see a rheumatologist? I assumed that's what you meant when you said you see your doctor next week.
I ask because I've corresponded with a few people online regarding this LDN therapy, and all of them said not to be surprised if your rheumy has never heard of this or won't prescribe it even if they have. Most said they had better luck with their general practitioner when it came to getting a prescription, but even then, I guess it's often not easy. One website I was on (I can share it with you if you're interested) even had a page you could print out to give to your doctor to read...it was designed to be brief but informative, to maximize the chances that your doctor would at least become informed as to the way the drug works and how it's used for autoimmune diseases.
The problem with getting a prescription for an autoimmune disease lies in the fact that because this drug was developed many years ago for another purpose (to combat opiate addiction--e.g. heroine, etc.), it's now generic. Since it was generic before it was discovered to be helpful for autoimmune diseases, no drug company will spend the money to do the research to prove that it's helpful for that use, as they can't charge big bucks if it works, and so wouldn't recoup their research dollars.
Because of that, the naltrexone is only available in the 50 mg. dose, and not the lower (3-4.5 mg.) that's useful (supposedly) for autoimmune diseases. This means that if you can find a doctor to prescribe it for you, the prescription will need to be sent to a "compounding pharmacy" that will make up the low-dose pills for you. There are lists of these pharmacies on some of the websites, and they will mail you the prescription once it's made up.
There's a second way you can go about getting this medication, and that's to buy the 50 mg. pills from a Canadian or Indian pharmacy, then you crush the pills and split them into the smaller dosages yourself.
It sounds kind of fly-by-night, I know, but there are so many people who say this has helped them tremendously, without any of the life-threatening side-effects of the biologics. I have read some comments by people who said they tried this and it didn't help them, so it's not a guaranteed thing, but I'm thinking about trying it.
Another noteworthy piece of information is that you can't be on any immunosuppressive drugs when you take this naltrexone. (I read that you can be on prednisone as long as it's less than 10 mg. per day, and ibuprofen and other NSAIDS are ok, but no methotrexate or biologic agents). This is because (again, supposedly) that the naltrexone works by making your immune system that of a normal person, and so immunosuppressive drugs would combat this.
Each dose works for one twenty-four hour period, so you take one dose per day, and it's to be taken between ten p.m. and two a.m. I can't remember the exact reason for this, but it's something to do with the natural rhythm of our immune systems.
Well, I'm sorry I went on so long about this, but I thought I would give you the gist of what I've learned about it, in case you wanted to look into it yourself. Again, I have some websites that seem "legit", and would be glad to share them, and if you come up with any, I'd truly appreciate if you'd share them with me.
I started a new thread with "LDN" as the subject, but no one has posted on it yet...I was interested to learn if anyone had tried it or knew anything about it. From what I read online, it's been used most extensively for MS, followed by RA, but it's supposed to help with other, non-autoimmune problems as well...Parkinson's, some types of cancer--there was quite a list. Again, this is what I've read, not what I know to be true.
Well, I've rambled on far longer than I meant to--I hope I haven't put you to sleep!
Thank you, too, for your correspondence! 