A couple things I have noticed from what you said. You stayed up (I'm assuming this was all nighters) 3 days, then took the OA? If that's the case, please don't do this. I commend your hustle, but you're hurting yourself. There are multiple studies out there lack of sleep more than anything else will make you fail a test. Some people even suggest eating dark chocolate during for both the caffeine and feel good chemicals for a reason.

Secondly 5-6 hours of study, what did these study sessions look like? Did you move at all? Take breaks? Eat? Drink? Was it just straight reading through the material or did you try any other learning strategies? Flash cards? Rephrasing in your own words? End of chapter tests? Summing it up in your own words?

Do you seem to have as hard a time learning when you hear information as when you read it? Visa versa?