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It may not have any relation to the C-section!?
It could be a referred pain
from the vertebra - X-rays of the spine and chest may give a clue.
like ESR (Erythrocyte Sedimentation Rate
) may point need for more investigations...
Gastritis can be confirmed by endoscopy
Heart pain may be excluded by TMT (exercise EKG)
Try a second opinion
Wishing speedy recovery