I have a 9 month old labrador that has been in season for a day over 3 weeks.She is very swollen at this stage.How long is she likely to stay like this?

she should be coming to the end of her season very soon,my bitch is normally in season for 23/25 days
the swelling takes a little while to reduce,my bitch stays swollen up to 4 weeks at the most from start of season that this.
mandy