Headache + one tiny pupil & one huge one. Docs seem stumped! What gives??

So this morning I woke up with a splitting headache on my left side that felt like it was pushing my eyeball out. My vision was blurry so I headed to a mirror to see if it looked different. I quickly realized my left eye is blood shot and the pupil is tiny compared to the other. Called the doc who said they wanted to see me immediately. When I went in they took me straight back and acted like this was some huge deal resulting in a ambulance ride to the E.R.

Apparently having one pupil much smaller than the other is a sign of brain issues so they did a brain scan and it came back ok. They seemed completely stumped at what was causing the issue. After the doctors consulted with the internet they said I either needed a neurosurgeon or a optometrist and sent me on my way with a scrip for hydrocodone to help with the headache.

With Monday being a holiday I cant even call a specialist until Tuesday at the earliest. Needless to say having one huge pupil and one small pupil looks creepy as shite. Its like staring at Marilyn Manson in the mirror. That combined with the headache and blurred vision has me worried.

Any of the OT crowd have any idea what can cause this other than brain issues? From what I read its usually caused by tumors, blood clots, stroke or severe head injury. I know it can't be that since the scan came back normal.