Does my crossbite warrant braces or just a mouthguard? My doctors can't give me a clear answer. (photos)

I had braces for 3 years. A crossbite developed after removing them. Every dentist I've had since then says this needs to be fixed. I'm now 27 & the crossbite is an issue. I can't bite down/tear off food with my front teeth. The only teeth that touch are towards the back. I have jaw pain, causing migraines. My dentist said braces are the only solution but I had an orthodontist tell me I just need a nightguard. Are braces, like Invisalign, the only way to fix this?