Last Friday, Kings of Leon had to cut short their Dallas concert when singer Caleb Followill left the stage due to heat exhaustion.

Now, the entire current leg of the band’s tour has been cancelled — and it sure looks like more than the heat is to blame. Uh oh.

“We are so sorry to say Kings of Leon are canceling their entire US tour due to Caleb Followill suffering from vocal issues and exhaustion,” the group said in a statement. “The band is devastated, but in order to give their fans the shows they deserve, they need to take this break.”

Before issuing that statement, however, two-thirds of the band took to Twitter to make it clear that other issues factored into the cancellation. “Not so good morning 4 me today. Ashamed & embarrassed by last nights fiasco. Can’t apologize enough, utterly gutted. A million I’m sorry’s,” wrote drummer Nathan Followill. Bassist Jared Followill was even more blunt, tweeting, “I know you guys aren’t stupid. I can’t lie. There are problems in our band bigger than not drinking enough Gatorade.”

Kings of Leon cancelled 28 dates in all; the band currently hopes to return to the stage on September 28 in Vancouver, making up for a show that was originally scheduled for September 14. Here’s hoping they can straighten out whatever ails them in the meantime.