A pal of Chelsy said that she was left shaken by the incident.
"It was a very frightening day for her. She collapsed in agony just after breakfast and was suffering severe pains in her stomach," The Sun quoted the pal, as saying.
"She had no idea what was wrong and was worried it may be linked to a tropical illness she may have picked up on her recent holiday with Harry to Botswana," the pal added.
Doctors kept Chelsy in hospital for observation for a few days, but she was feeling much perkier the next day as she sat up in bed joking with hospital staff.