Sticksman left metal outfit in 2013
Departure was down to illness
Hospitalisation postpones joint tour with Marilyn Manson
Frontman performed 'Sex Type Thing' with DeLeo brothers and drummer Matt Sorum
Group have released first single 'Simple Skeletons' ahead of debut album release
Frontman reveals band have been asking, "Where do we go?" recently
"It's shocking that nothing is sticking to him"
Singer previously said he 'might step away' from the metal outfit
Frontman raises doubts over group's long-term future
The co-headlining stint will take place in the summer