Rahm finished two rounds at even par and will not make the cut at Valhalla Golf Club.
Rising star Atthaya Thitikul birdied five of the final seven holes in a round of 7-under 65.
LPGA officials are concerned about health issues at the Mizuho Americas Open.
Having begun Friday in the most unforeseen of settings, Scottie Scheffler ended it in an entirely expected place – in contention at the PGA Championship.