DENVER (KDVR) — Public health officials are warning about the rare side effect of women suffering blood clots following the Johnson & Johnson COVID-19 vaccination.

On Wednesday, a 60-year-old Denver man named Danny Sweeney said he too suffered a blood clot after receiving the J&J vaccine.

Sweeney said he got his vaccine at a clinic located at an Adams 12 Five Star Schools district office in Thornton (1500 E. 128th Ave.).

Sweeney showed the FOX31 Problem Solvers medical documentation indicating he was treated at Centura Health’s Saint Anthony North Health Campus from April 8 to April 11. He said he was diagnosed with pulmonary emboli (a blood clot in a lung) in his right lung.

“I couldn’t breath,” Sweeney said. “I couldn’t move. It was just the worst pain ever.”

Sweeney said he is lucky to have gone to the hospital when he did, “If I would’ve waited another day, I wouldn’t be here doing an interview.”

He says he has always felt healthy and never had a problem with blood clots before this incident.

He first went to the hospital due to chest pain on April 1, just less than a month after getting the J&J vaccine. Sweeney was inoculated against COVID-19 on March 6.

Sweeney said he felt ill the day after his vaccination and he only felt worse until he was treated.

While current evidence points to women rarely suffering from blood clots, there are still many unknowns at play. There’s an ongoing federal investigation into the J&J vaccine.

Due to federal privacy laws, Centura Health won’t confirm if Sweeney’s case is being investigated for a potential link to the J&J vaccine.

Centura has confirmed that one person is currently being treated in its system who is being observed for a potential adverse vaccine outcome.

Doctors stress blood clots are exceedingly rare following the J&J vaccine. 

This is a developing story.