The veteran rocker was performing with his group Further in Port Chester at the end of April (13), when he fell to the floor in the middle of a song, and then exited the stage with what bandmate Phil Lesh called a "strained shoulder".
Weir was back onstage with the group in Atlantic City, New Jersey on 27 April (13), but an ongoing mystery health issue forced him to scrap a series of appearances and shows, including a performance at the BottleRock Napa Valley music festival in California.
A statement from the band read: "Grateful Dead & Furthur co-founder Bob Weir is unable to perform in any capacity for the next several weeks."
However, the guitarist returned to the stage on Wednesday to tape a new episode of his weekly web series, Weir Here, which has been on hold since his stage collapse, in front of a live audience at Terrapin Crossroads in San Rafael, California.
Weir offered no official explanation for his leave of absence, but appeared to be in good health and spirits as he performed with Widespread Panic's Dave Schools, Primus' Jay Lane, Jeff Chimenti from his band Furthur and multi-instrumentalist Jason Crosby, among others.
The show also featured a performance from singer/songwriter Beth Orton.
Weir then sat down to chat about his high school memories with Grateful Dead archivist David Lemieux and answered questions from the audience, but no one asked him about his health.