I feel like this might be a joke, but just in case.

Could be anxiety. Lots of tips online. Square breathing and meditation comes to mind. Also there’s medicine doctors can give you.

For what it's worth, I'd rather trust the person who is unsure if they are correct, than the person who's confident that they can't be wrong.

Think. Try thinking. Do calculations. Do argumented predictions.

stop feeling it.

I view this as a good thing. My bacheloreate was in science and I can tell another science type person like me by the way they hate saying something is not possible or definate. They shy from zero and 100%. If I say something is 99% then im sure if I say less than 1% and im sure its not gonna work.

Understand the process you made to get the answer.

You can try accepting that uncertainty is completely normal and healthy and can be your minds way of letting you know you need more information or more time to process the information you already have. No matter what, be honest about it with everyone involved. We all have to make decisions sometimes without enough information and sometimes even with none. Guessing can feel overwhelming but it always helps me to be honest when guessing is ultimately what I have to do. Making a decision when you are uncertain can be very uncomfortable but doing it and seeing that you survived can often help ease the discomfort next time. Good luck!

that's good because uncertainty is the reality, it's certainty that is a myth propagated. historically there is always people trying to capitalize others' desire to avoid uncertainty, inventing religion, snake oil, supplements, etc.