And the doctor said.

I saw the doctor, and he said 'Oh dear. You need to see a specialist.'
Which, on Friday afternoon, isn't easy.
So we went to the St John of God Emergency department. (They're so nice there, I thoroughly recommend it)
The long and the short of it is, the blood tests came back fine, and I'm booked in for an MRI on Monday afternoon so that they can, hopefully, rule out tumours and the such-like.