we have well water but it tastes like blood, thinking it could be rust

Tetanus is not a poisoning. Tetanus is a condition(infection) caused by a bacterium called Clostridium tetani .

It grows well under anaerobic condition(lack of oxygen).

So it is more associated the conditions related to rusted iron as there is less oxygen in that environment. it is because of oxygen in the area being used up in rusting process.

you can check the symptoms here.
mayoclinic.com/health/tetanus…

Hope it helps you

Have you had your tetanus vaccination in the past 10 years? if so, you should be okay.

Symptoms: emedicinehealth.com/tetanus/p…