Some memories can last a lifetime, but really shouldn't.
Parasites! I can tell you stories, for sure.One young man came to volunteer after the earthquakes and came down with a stomach bacteria. I asked him if he wanted someone to take a specimen to the lab for him. He insisted it was getting better. In a few days, the bug would be back. About the fourth round of him insisting it was getting better, he finally consented to have someone take a specimen to the lab.
When it came back 'nomal' I inquired to the person who took the specimen to the lab. As it turned out, the lab personnel asked Krishna, "What is it, urine?" Krishna wasn't sure, so he did what every well-meaning Nepali does, he agreed with the man. So it was tested as if it were urine and had nothing associated with unhealthy urine.
It was only at that point that the young man consented to see a doctor, which ended the problem. My reason for sharing the story isn't just to tell a funny story at a volunteer's expense, but to help you see the seriousness of the issue. Some of these parasites can attack your organs. Few doctors will think about parasites and I wonder how many people have been wrongly diagnosed with írritable bowel syndrome or even crones disease who simply had a bacteria hiding in his bowel. During the Indian border closing last year it seemed about 25% of our guests reported having had an issue. This was due to the lack of petrol, which had gone up to $5 a liter and was only available on the black market.
So, on your last full day in Nepal, if not sooner, you should go to a pharmacy and purchase 1 dose of de-worm medication. Do this even if you do not have symptoms. These worms are contagious and could affect someone you care about worse that it seems to be affecting you. Do not take the chance that your body will throw it off. If you are not convinced about the seriousness of this issue please read the following article: https://en.wikipedia.org/wiki/Albendazole
Additionally, as I wrote in my eBook, "Nepal: A Tourist's Manual," if you become ill while you are staying in Nepal you can have the guest house owner have a doctor come for only $5-10 and hopefully closer to $5. He will bring a sterilized container for a specimen and some medication. The option would be to go to a hospital, but that is quite difficult for a tourist with diarrhea.
So, what is the 'One last thing to do before leaving Nepal?' It is to go to the pharmacist and get one pill to take that day and another one just in case you start getting intermittent bowel issues after you get back home. This will cost less than $1 and will have the added benefit that you won't pass this onto others.