As I write, I am sitting in the hospital with my son falling asleep beside me. It turns out that this was all due to Lyme disease, which caused Lyme meningitis! After doing some research over the weekend, I spoke with his dr on Monday and he ordered a Western blot Lyme test, which came back positive on Wednesday. Brought him to the hospital for a spinal tap, which came back positive for meningitis and the ELISA test was also positive for Lyme. He will be going home in a day or two with a 28 day course of IV antibiotics. We are thankful that the blurry vision showed up to have us question it further, and he should be fully healed after the 28 days have passed. He is already feeling better with the IVs they are giving him in the hospital.
Thank you all for your advice and well wishes--it's nice to finally have an answer and not have to keep wondering!!