I have a complicated medical problem/history, and need to know where I can go/what I should do to get some actual help for my problem.

My history:
Depression/anxiety since teenager- treated with Lexapro 5mg,
POTS (postural orthostatic tachycardia syndrome) approx 7 years ago- mainly resolved, but can still have flares of tachycardyia,
Interstitial Cystitis 6 years ago- managed with diet
IBS (abdominal pain, food intolerances, brain fog) 5 years ago- managed with diet but easily aggravated with medication/supplements, etc.

I've been experiencing chronic facial/sinus pressure/pain and corresponding brain fog and depression for the past 2+ years. I began having mild issues 6 years ago following a sinus infection that mainly caused some brain fog, fatigue & sinus "pressure". The symptoms became more problematic and 2+ years ago, a trip to Minnesota and change in living environment caused a huge flare with increasing symptoms- facial pressure and pain, mental problems. Allergens (dogs, cats, molds) and various other triggers (candles, chemicals, foods) can exacerbate symptoms and can cause pain, but the pressure (feels like inflammation) is constant and is coupled with brain fog and depression. I have so far seen 3 allergists (no allergies based on blood work), an ENT (clear CT scan), a neurologist (clear MRI), a rheumatologist (no autoimmune issues as far as she could tell based on labs. Inflammatory markers okay except some white blood cells high), and 2 pain specialists and all I have is a diagnosis of atypical facial pain.

I believe my issue is nerve/immune related, but I have no idea who to see who can actually offer any help.

The only thing I have found that helps manage the pressure/pain/cognitive issues is prednisone- 10 mg /day. No doctor likes me taking this, but I have no idea what else to do, and they don't offer any good alternatives. I've also had trigeminal nerve blocks which helped for a few days, but this may have been because steroids were used. I felt the best I had in years while on Macrobid for a bladder infection and a week following (could I be overreacting to bacteria in my sinuses?). This was the only time I've been able to get off prednsione in the past 1.5 years. Gabapentin works somewhat, but increasingly less over time. Lyrica seemed to help, but I became depressed while taking it over the course of a few days. The latest pain doctor I'm seeing did a sphenopalatine ganglion block, which had a curious result of decreasing some mild pain, but made the pressure/mental issues slightly worse.

I also take antihistamines and singulair. Antihistamines that cause drowsiness work the best, but I cannot tolerate them everyday.

I cannot tolerate anything up my nose (steroids, antihistamines, nasal sprays). Most everything I put up my nose only makes it worse. I cannot tolerate SNRI's and they don't seem to help much. I cannot tolerate NSAIDS and they don't help enough either. Nortriptyline makes me depressed. I've tried fish oils, b12, and every other supplement under the sun as well.

I asked my pain doctor about how I should address the inflammatory sensation/pressure/brain fog/depression (I experience this all as one symptom) that I treat with prednisone, and he ignored me. And this is basically the same response I've gotten from all the other doctors with advice to taper off the prednisone and try the latest antidepressant.

At this point, I'm not even hoping for an exact diagnosis, I'd just like help treating the primary symptom- inflammatory sensation/pressure/brain fog/depression. Who specifically can I see and what types of treatments will help with this issue? I feel like I keep throwing money at doctors trying to get relief, and it's getting me nowhere.