A question of pits and stomachs
"Pit in my stomach" is still controversial, and is considered by some to be an error, including Professor Paul Brians, of Washington State University, who has included it in his book "Common Errors in English Usage", alongside such gems as "ad nauseum", and "along the same vein". Mark Liberman, writing on Language Log, traces it as far back as 1980, and calls it an eggcorn.