Every so often a villager will come down with some type of mysterious illness, They will not leave their home for the entire day, will have visible shakes, sweating, sneeze and cough. Often times wearing some kind of night clothing as if they never dressed for the day, pacing slowly through their home they will appear to be struggling and visibly upset.
Other villagers will sometimes bring it to your attention in a gossiping manner. If you do not bring your sick neighbor medicine they will remain ill for a several days. Villagers will continue to tell you about their illness, sometimes suggesting that you visit. Ignoring the sick villager will greatly reduce your friendship level.
If you want to be friends with your villagers it’s best to bring them some medicine and offer it to them. You can buy medicine at Nooks Cranny for 400 bells, or you can make your own assuming you have acquired the DIY recipe.
The recipe consists of a wasp nest and some random weeds that you can collect anywhere on the ground. It does not matter what type of weeds they are or what they look like. Any weed will do apparently. The seemly random concoction will cure any illness from any villager anytime in the blink of an eye, as the game's secret health-force God works her instinctual magic in the background. The villager's flu-like symptoms will disappear in an instant as they spin in a circle of joy. Your friendship level goes up and by the next day your villager, no matter how sick they were, will be back to their normal selfs.
The villager will be grateful and often times give you a thank you gift in return.