Also be aware that very often turbulence is associated with a change in wind speed and direction, you may have just run into a 90kt headwind.
Also, in that area (Azores/Cape Verde Islands area) we commonly notice wind changes, from a tailwind to a headwind (heading Eastwards). I fly JFK to Johannesburg, and have experienced 150kts tailwind to 300nm from Ilha da Sal, with a change then to 40kts head on from Sal, with the associated turbulence. So that could well be part of what you have had happen to you.