It looks like my case was pretty mild in the end. About 1 day of severe fever, 1 mild, half very low. Diarrhea from the beginning, it started pretty slow but got intense. Overall duration about 4-6 days.
I've been taking at least 1000 D3 per day, but ramped it up to 4k during (taking meds right after I had to run to the toilet). I also took a at least a generic vitamin per day. Otherwise I had a lot of Corenza C Aspirin, which was ok for the mild fever.
For water/rehydration I kept on sipping water (or doing oral rehydration recipe: 1L water + 6 flat teaspoons of sugar + 1/2 teaspoon salt).
For food I ate some basics that are ok for a bad stomach like crackers, plain rice, etc.