Ariana Grande is telling her fans that she has a bad sinus condition that has made her “very sick” and might force her to cancel upcoming shows on her world tour.

Grande, 26, says in videos posted Saturday on Instagram that “my throat and head are still in so much pain.”

While she sounds OK, “I’m just in a lot of pain and it’s difficult to breathe during the show,” she says in a message to her fans. “I just really don’t know what’s happening with my body right now and need to figure it out.”

Grande says she plans to see a doctor soon.

She adds: “I’m scared that I might have to cancel some things, so this is kind just a heads up of like I don’t know what’s happening with my body, and I’m really disappointed and freaked out of why I can’t get better because it’s been over three weeks at this point.”

People magazine first reported on Grande’s Instagram videos.