
Yes, the mammary glands become swollen due to the hormones. She'll likely go on to have a (hopefully mild) phantom pregnancy.
How long is it since you first noticed her bleeding? You need to count the first day you see the faintest hint of blood as being Day 1 and keep her isolated from other dogs for at least 21 days - 28 to be on the safe side. Often the discharge becomes paler and more straw-coloured after 10 days or so - this
does not mean her season's finished - it means she's in the fertile period and you must be even more careful!