I use the site webmd.com quite a bit to kind of get an idea of how worried I need to be about certain health issues. They have a symptom checker where you can put in your gender, age, and symptoms, and it will list different things that might be wrong. If you put in "partial vision loss," you get a pop-up that says to seek emergency medical attention ASAP. Then it asks if the vision loss is sudden or gradual; if you say "sudden," it again tells you to seek emergency medical attention ASAP. So, I would probably go to the ER.
My two cents on government-run insurance - Just because you have Medicaid doesn't mean you're a bottom feeder. We have All Kids/Family Care (part of Medicaid). It sucks because it's hard to find a dr who will take you as a patient if you're not already established with their office. But, I don't really think it's any worse than the private plan I had before. Due to a unique employment situation, I didn't have access to a group plan and had to get an individual one through BCBS. That also sucked b/c if you don't have the consumer power of a group behind you, BCBS doesn't really care about you and will look for any piddly reason to deny a claim. DH couldn't even get insurance through them because he had surgery for scoliosis 10 years ago. So, basically, we went from one crappy insurance to another, but we don't have to pay for this one. And, to be fair, it has been a huge blessing for basic services like check-ups and the flu, since we were already with drs who took the plan. But trying to find a specialist to see you for anything is next to impossible, and if you have to switch pcp's...good luck.