Personally I think he has jumped the gun with a scan but not to worry! Break through bleeding is really common with HRT and although a scan is a must for post meno women not on HRT drs usually wait and see if you are HRT.
I'm a bit confused- was this a bloody discharge or just a normal 'wet' clear discharge that you posted about at the start of your thread?
That's what you'd expect taking oestrogen.
If you are now bleeding after having stopped 1 sort of HRT and are just stating on a new kind, then bleeding is to be expected depending what you are taking and the level of the 2 hormones in your body now. Any changes to the usual amount of either oestrogen or progestogens can cause spotting/bleeding.