Harwell was rushed to the hospital in an Uber directly from soundcheck, and is now stable.
According to TMZ, Harwell suffers from a heart condition called cardiomyopathy, which makes it difficult for the heart to pump blood. Harwell has been living with cardiomyopathy for two years.
Smash Mouth ended up cancelling a few dates, but they're back in action tonight in Elgin, IL.
We're sending Harwell and the whole Smash Mouth team our best wishes!