What would cause a 61year old person have low iron all of a sudden?

 it's very common for older people to have mild anemia — meaning a hemoglobin level that's not way below normal — and in this case, symptoms may be barely noticeable or non-existent

Can you list the drugs that you want answered for? i think maybe your answer could be a or b. but i’ll never know till you post the rest of this question.

It’s a because it says during exercise so they are doing a athletic activity