LDV cub van back brakes gone.

Yesterday my back brakes felt like they had gone. The result of driving with the handbrake on! But today they feel fine. I noticed that they had gone by the white smelly smoke coming from the back of the van (ldv cub) and then the brake pendle feeling like it could be pushed further down than normal and it taking longer to stop. The brakes today don't smell, or smoke and the pendle and stopping speed feels normal. Do you think I still need to change the breaks? And would I need to do all four or just the back ones? Thanks, c