I think there are several factors in play for the reduced number of cases. I don't see what the Dr. says as being a lie. Masks, distancing, etc have a big effect on reducing the spread. We also haven't had any "gathering" holidays since New Years and to me that may be the biggest difference. The Thanksgiving, Christmas, New Year's spikes have played out. Add that to 20% of Alabama's population have had the virus or have been vaccinated which reduces the pool of those who would be vulnerable.
Mask usage and distancing haven't significantly changed over the last few months, crediting a variable for a drop that was also in place during the rise is misleading at best.
I strongly disagree with your second point. The gatherings you reference simply fell during the time while the virus was rapidly spreading, they were not the cause of the rise. They may have enhanced the rise slightly, but those gatherings were little more than noise in the overall signal. Why was virus activity decreasing throughout the holidays across the plains, rockies, and upper midwest? Their peak was just as high per capita as it was in the southern US, but it came before the holidays. Here's a plot of some of those states and Thanksgiving/Christmas plotted on it
Even in Alabama, cases and hospitalizations started increasing rapidly in late October. Up in your area, northern Alabama rapidly increased throughout all of November. Here's data from the Huntsville Hospital system from the Monday before Thanksgiving. (this value also increases to 307 by Dec 1, and that's likely before any supposed Thanksgiving increase would be seen)
I do agree that the combination of the amount of people that have had it and people getting vaccinated are likely contributing to the rapidness at which it is currently decreasing.