Just reporting back for some closure. These are my final conclusions:
1. The off-the-shelf protein drink definitely didn't help with my BM. Culprit #1. I will avoid processed food with higher alert in the future.
2. What scared me as "hard stool" in the following days were not necessary really hard in texture. They appear hard since they were more "formed". It's because of this hemmie supplement that I was taking which had psyllium husk in it. They also felt very hard since my anal canal (and sphincter muscles) were still damaged and even the slightest "scraping" made them mad. I took this supplement out and BM has been loose since.