Before their return to Hogwarts, Harry visited Gringotts. In the Black portfolio, they found a house in a small town in Wales that would suit Sirius better than Grimmauld Place. Afterwards, they ordered a wardrobe that suited his slimmer frame and was suitable for a Lord Black. Finally, Harry talked to Andromeda Tonks, or more, let Sirius speak with her. His godfather seriously needed a competent mind-healer. On his own, he would never get better.