Help with 1 missing Experience at Searock Castle

Hello everyone,

I'm having trouble finding 1 missing Experience (level experience, not monster experience) at Searock Castle. The thing is, I've played that level through multiple times. And on a heads-up, I've already gotten the one near the crumbling bridge. I already got the ones on the seashell.
I've seen walkthrough videos for finding all experience vials/jars on Youtube, searched on Google to see if I could find some information... But nothing so far.

I've looked everywhere, from repeatedly swimming underwater to see if I missed any found on the water to building a 4-block tower to check on higher places, re-checked secret places I found before to see if I missed it on these places... But it's still nowhere to be found.

I know that the information I've given here is probably not much help to anyone trying to help me out... But this is all info I've got.

Can anyone help me here? And thanks in advance!