Elvis's Dallas No-Tell Motel; inquiring minds (especially mine) want to know more

I am currently reading Alanna Nash's biography of Elvis Presley called Baby, Let's Place House. and came across this paragraph:

"On the way to play his Vegas dates that August (1975), he again had trouble breathing on the plane. It made a forced landing in Dallas, and after recuperating in a motel for several hours, he continued on."

She did not cite a source for this information in the book's Endnotes. Does anyone have any additional details about this episode?