What should one do if they doubt a pillar of prayer, such as reciting Al-Fatiha while bowing?

Whoever doubts having omitted a pillar of prayer while in the midst of it, it is as if he did not perform it. If a worshiper doubts having recited Al-Fatiha while bowing in the same rak'ah, he should stand upright again to recite it, then bow and perform the prostration of forgetfulness (sujud as-sahw) after the salam. As for the congregant (ma'mum), the majority of scholars believe that the recitation of Al-Fatiha is waived for him.