Peppermint oil used for digestion problems?

When I was in India several years ago, I was suffering from stomach problems and the family with whom I was staying gave me this amazing stuff which really worked, maybe some kind of peppermint oil. I was told to put just a couple of drops of it into a glass of water, and take it after every meal for a few days. After only 2 days I was cured and the problems I'd been having never came back.

Does anyone know what this is, and where I might be able to get hold of it? I live in the UK but as we have lots of people from India living here I probably should be able to get it somewhere.

Thanks!