The left-hander landed awkwardly on his 107th pitch and was helped off the field.
The Rockies starter allowed five runs on seven hits in 5⅔ innings. He struck out two and walked four. He was charged with the loss, falling to 1-5 on the season, as the Nationals defeated the Rockies 6-5.
"On push off, just felt a shooting pain at the top of my foot right at the joint kind of going down my foot,'' Freeland said. "I have no idea what it was. I've never had it before, but it was good that X-rays came back negative. We think it was just a little bit of impingement there, so we'll see how I feel tomorrow.''
Manager Bud Black didn't think Freeland will need to go on the injured list.
The Associated Press contributed to this report.