Failed a class in my first semester of vet school, not sure what I'm doing wrong

I completed my first semester of veterinary school and was notified today that I did not pass one of our main courses, anatomy and physiology. I had been struggling all semester but was fighting desperately to improve and catch up to everyone else. There is no sob story here, no long list of excuses as to why I feel I was wronged because I wasn’t. When the semester started, we all were hit with the massive tidal wave of information. If this had been a race, it was as if everyone else stumbled but figured out how to keep on running, whereas I fell on my face and had been desperately trying to keep running on one leg. I have never struggled with memory retention or memory recall like this before, especially with something I am so passionate about. When I failed our second exam, I met with tutors weekly, changed my study habits, tried new study methods, anything I could to try to fix this and nothing seemed to improve. I understand the concepts when I am learning them but by the next day it’s as if my brain purges the information, I can hardly recall it and have to re-learn it all over again. By the end of the semester, I was spending ~ 6 hours a day outside of class reteaching myself topics but I can only fit so many topics in at a time. The topics I didn’t have time for were then brain-dumped and I’d have to start all over. I unfortunately didn’t fall into a close friend group and when I asked different peers if they would want to study together, everyone would say they were either too anxious to study as a group or too far behind as well. I respected that of course but struggling alone really sucks.

Now my only option is to be held back a year and as an older non-trad student, that is almost as devastating as the failure itself. I don’t know what I’m doing wrong. I excelled in all of my other courses, getting high As and 1 high B.

I guess I’m just looking for insight from others who have been in my shoes. I know veterinary school is made to be hard, but I have never struggled with memory retention or information recall like this. I’m terrified and grieving, mostly because I don’t know how to fix it or why it’s happening.  

TLDR: failed one of my classes in my first semester of vet school and now have to be held back a year. I can hardly remember concepts longer than 24-36hrs and don’t understand what's wrong with me.