I have had CFS/ME, the equivalent of long covid, for 5 years now.
While 9 months does not sound like a long time to suffer with this, it is absolute hell if you keep accumulating symptoms and being forced to push yourself because there are 0 treatments for this disease.
Those around you will pretend like your suffering is not real, it is exaggerated, it's all in your head, and other rubbish. All while your cognitive abilities decline, your body deteriorates (you won't be able to exercise anymore) and your loved ones abandon you for lacking energy to engage in activities.
It's not difficult to see how 9 months of that will drive you mad. Especially when you realize there is no cure.