The 'Fins were set to have a joint workout with the Philadelphia Eagles ... but as it turns out, some guys could barely sleep because they were blowing chunks all night.

NFL Network's Mike Garafolo says some players thought all the vomiting was due to food poisoning ... but the team checked what everyone's been eating, and haven't found enough proof to back that theory.

Dolphins head coach Mike McDaniel says the team believes it's a stomach bug going around ... and to be extra cautious, they decided to keep everyone home to make sure it doesn't spread.

Miami and Philly are set to play against each other on Saturday ... and so far, things are still set to go down according to plan.

Coach says he wanted to take extra caution to get everyone healthy for the matchup -- especially because the last week of preseason is crucial for so many guys who are trying to make the team.

As for how many players were affected, McDaniel says it's more than a few, but not half the team.