Offtopic. I recently bought a juicer. But turns out that after drinking one glass of fresh orange juice, my face turns pale, and I start sweating. It's nothing serious (I hope), but curious if anyone can recognize/explain this phenomenon? I have no such effect when eating large amounts of sugar. And I have no known allergies (recently tested in the hospital for another issue).
… did you ask a doctor about this? You should be asking a doctor about this. Not people like me, who'll tell you this sounds like a potential vitamin overdose or something.
You may have developed an allergy to Oranges. I grew up drinking orange juice and eating oranges my whole life and a few years ago I developed an allergy to them and a bunch of other common foods. I'd bring it up with your doctor and get tested for it (along with other common foods). Apparently an allergy to oranges is fairly common.
Look into oral-allergy syndrome. When I've experienced it, it has only meant that I hadn't had X (oranges, celery, etc.) in a long time and it would dissipate as I ate more X.
Restaurants always advertise "Freshly Squeezed" orange juice on their menus, but that's become meaningless. I like to ask the waitstaff "Was your orange juice squeezed here, on the premises?". If the answer is "no" I usually order something else.