Coin-Shaped Opacities in the Stomach

On day 7 after hospital admission, a patient with end-stage kidney disease prescribed sevelamer, hydrocodone-acetaminophen, hydromorphone, and chewable lanthanum tablets developed intermittent apneic episodes, bilateral rhonchi, and responsiveness to verbal commands only with deep painful stimulus; a chest radiograph showed 4 radio-opaque coin-shaped opacities in the stomach. What is the diagnosis and what would you do next?
Source: JAMA - Journal of the American Medical Association - Category: General Medicine Source Type: research