What's Wrong With 30 Rock's Tracy Morgan?!

30 Rock star was spotted being pushed in a wheelchair through Denver International Airport

Tracy Morgan and altitude don't mix.

In Colorado for a show, the 30 Rock star fell ill enough that he needed wheelchair assistance to make his flight home from Denver International Airport.

So, what's wrong with the at-times fragile funnyman? And is he going to be OK?

"Feeling a little better.. had to call in sick on Saturday," Morgan, 43, tweeted today. "I'm sorry I had to cancel. Love you Denver. I'll make it up to you."

The comedian's rep explained to E! News that he's doing "fine" now but had the flu before he even left for his trip to the Mile-High City. TMZ reported that he spent a few hours at a hospital being treated for flu-like symptoms and dehydration.

Said to be sickened by a combination of exhaustion and altitude, Morgan collapsed during an awards dinner at the Sundance Film Festival in Park City, Utah, in January.

—Reporting by Holly Passalaqua