I don't think any attention has been paid to the word 'och' as used by the Scots. 'Ach' means 'but' in Gaelic whereas 'och' in Lowland Scttish is a kind of emphatic way of saying 'yes' (aye).
In Paisley where I grew up, there was a tendency always to end a sentence with 'but'. I never realised this until I was in Germany and said 'aber' at the end of each sentence! Perhaps 'och' and 'ach' are related?