Neutral, I was feeling the same as you a few months ago, I tried just taking allergy medicine to prevent POIS for a while and it just wasn't enough. I'm now taking a bunch of new supplements and they are working really well, they still only take away the worst parts of POIS though and not the whole thing, so I'm also seeing an endocrinologist in two weeks. I agree with you healthcare in the U.S. is pretty horrible, I did have a pretty easy time getting an appointment, but I've had to wait a few months and its expensive. All I had to say was that I was having trouble sleeping, and that I wanted to get a cortisol/hormone panel. I plan on mentioning that I have POIS, bringing the printed wiki article (with references). The POIS wiki looks official and lists endocrinology right at the top, and I'll bring the study which includes the POIS symptoms survey to corroborate it. Finally, I'll bring the study which defines the first marker for POIS, decreased vagal tone and decreased heart rate.
Like Going Less Crazy said, try to get hard evidence of something that is wrong, because then the doctor would have to do something about it. Off the top of my head I can't think of anything that commonly shows up on blood tests for POIS sufferers, but usually everyone has at least one or two levels of something that are abnormal. As a last resort, you could just show that your vagal tone goes down during POIS, but I'm not sure if that's something the doctor could do. Some heart rate monitors can do this. This is important because vagal tone shows how active your vagus nerve is, and beyond controlling some of the most crucial parts of your body it directly controls inflammation in the body through the chonlingergic anti-inflammatory pathway. If your doctor doesn't understand the importance of that, explain that chronic inflammation is involved in around 8 out of 10 of the leading causes of death in the U.S. and that it is now accepted medical fact that inflammation is a cause of depression.
Since the doctors are probably going to take a while, and I'm in POIS right now (without my supplements) and know exactly what you are going through, below is the list of what I've been taking. I researched them pretty closely to make sure they treated a cause of POIS, and did my best to make sure they don't interact with each other, but I tested a few out at a time so just use this list for suggestions DO NOT take all of them. Research these supplements yourself, ask your doctor about them, and build your own list of supplements that help you.
before POIS:
Mast Cell Stabilizers
Curcumin
Green Tea Extract
L-Theanine Stress Formula
Luteolin Complex
Quercetin (w/ Bromelain)
Fisetin
Rosemary
Vitamins
B-Right B complex
Methyl B12
Vitamin D
Vitamin C
Histamine clearance support
Antihistamine
Olive Leaf Extract
Immune system support
Anti-inflammatory
Huperzine A
Singulair (prescribed for my asthma)
Kyolic Moducare CF
Hydrangea Root
During POIS:
Acetyl L-Carnitine
Fish Oil
5-HTP
Ashwagandha
These supplements have made my life much better, although I undoubtedly still have POIS, many symptoms have almost disappeared. This includes cognitive ones, flu and allergy symptoms, intense discomfort, irritability and anxiety and depression have improved a decent bit. By far the biggest effect though, that has been on my mind since I started taking them, and which I can confirm now that I've gone through POIS again without supplements is that I don't feel like my entire personality changes whenever I have an O now. It still feels like a bad hangover for a few days, but its something that goes away fairly quickly with excericse. I have a spreadsheet I started where I explain in detail why I included all of the mast cell stabilizers and B vitamins (with some good research from examine.com and some medical articles). Was going to do the rest but then school started up and I've been really busy. Also I have been trying to cut some of these supplements out but each one I've either tested extensively or strongly believe they help POIS, but if someone has tried one of these with no effect or negative effect please let me know.