“Then I might be in need of actual medication to address my headaches, sweating and nausea.”

It’s actually not uncommon. People expect and manifest symptoms all the time.

What side effects a drug would be likely to cause, the pharmacologist likely knows long before ever giving it to a human. When the human reports side effects that the drug is unlikely to cause…that human was probably a placebo.

So i can get a headache only by placebo?? Wait, can it happen in reverse? Like, i have an headache and i convince myseld that i took a cure for it

Yes, and there’s actually some interesting results from this too. Pain medicine marketed as targeting specific pains, such as headaches or toothaches, are often just generic ibuprofen or acetaminophen, but there is some evidence that the pain medicine will be more effective if you believe it is targeting your specific pain. So whenever my wife wants an Advil I always tell her that it’s a special Advil that is for whatever specific thing she complained about.