If a doctor say that you have flu (either type A or B,) you can NOT go to school because of School Health and Safety Act (gakkou hoken anzen hou 学校保健安全法).
If you have flu, you cannot go to school 5 days after the day you started having fever (6 days including the day you have fever.)
OR
You cannot go to school 2 days after you don't have fever any more.
What the doctor can do for your flu is the symptomatic treatment. Which is - If you have fever, the doctor gives you the medicine for reducing fever. If you have body ache, the doctor gives you the pain killer for your body. So on. Basically, flu will be gone at some point if you have proper meals and sleep.
It's OK for your body to have fever because it means you body is killing virus by your body heat. And it's OK for you to have diarrhea and/or vomiting because your body is trying to get rid of the toxic out from your body. If it gets too much, then you would need to take the medicines.
Also, you could ask the doctor "Tamiflu" that blocks virus in your body.
https://www.drugs.com/tamiflu.html
Yet, because of the side effects and because you are not with your family, I don't recommend Tamiflu.
[English folks in and around Miyako]
At one clinic, I saw this sign. It says "There was the first flu originated report for this season between October 17th and October 23rd (42 weeks) in Miyako health center's jurisdiction. The epidemic can be spreading later this season. As a precaution, vaccination before the epidemic, hand washing in running water with soap, and wearing mask are effective."
I just had the vaccination this morning.
It costed me 3,800 yen. The cost for vaccination is different for each clinic, but usually it's 3,000 - 4,000 yen.
You could get flu couple times in the same season because there are different type of flu. So, if you are interested in taking a vaccination, I can take you Saturday morning. So, please let me know. Thanks!