I would find it very difficult to recommend a protocol that in your experience has such a short-term effect.
Encouraging people to violate the law by advising them to hord prescription medications without a prescription from a doctor is the issue here. If you are a medical student then you should KNOW that this is illegal, unethical, morally corrupt and downright stupid advice to give to people without a medical degree. If you don't know this, please let us know which hospital you end up working at and your hours so we can all avoid your ignorant and corrupt beliefs. Any license to practice medicine you receive should be immediately revoked if these beliefs are upheld in your professional career. You are scared and stressed about covid, I get it...but that will not be an excuse here.
Asking auntie to pass on the valuable knowledge she appears to have is nearer to adulation than denigration.
Back to the original question ... I bought a finger oximeter from Lazada for about 350 peso. It arrived in just a few days and works fine.
The trick is to: 1) Order from a supplier in Manila. The shipping takes longer for suppliers in China. 2) Do not order from a post that says "Pre-Order". This means that the Manila supplier does not have it in stock. Look at the time to ship in the post.
Could you give the name of the seller and oximeter you purchased, please. I note that Amazon.com is selling some at around P1000 equivalent and these are named brands and FDA approved. So naturally I would be concerned at using a health product which is less effective at doing its job. However, both yourself and @SkipJack are scientifically knowledgeable and have bought from Shopee/Lazada - so it would benefit members to know exactly which product you purchased.
If you go to Lazada and do a search for finger oximeters you will see hundreds of them listed. They range in price from under 200 peso to several thousand peso. This is the one that I got, and it works very good. I took it with me when I went to the hospital to visit a patient who was hooked up to a pole mounted hospital heart monitor / oximeter, I put mine on his other hand and the reading was identical, so I know it is calibrated. https://www.lazada.com.ph/products/...o4l.searchlist.list.2.143657c1s1hlxI&search=1
Here's the Shopee one I got: https://shopee.ph/Portable-Finger-P...Finger-Oximeter-(Black)-i.91409909.2774824894