Very normal, her hormone levels will be increasing and her uterus is preparing for the birth. The discharge may become thicker yet, but should remain reasonably clear or white, not green or black - if you see that before labour - its time for a trip to the vet.
Best wishes & try not to worry too much, cocker bitches are usually very sensible and as long as you keep a fairly watchful eye over them towards the big day ie daily temperatures & signs of labour starting etc - you'll both do fine!