I am not the owner of the Harry Potter characters.
Doctor, Doctor
It was Christmas time in 1995, and Harry was staying at Grimauld Place with the Weasleys, whose father had been attacked by a large snake, and he was thus recovering in St. Mungo's Hospital. The house guests were going to St. Mungo's today to visit him.
While they were awaiting their turn to talk to the receptionist, Harry was looking around and saw a sign listing the different types of treatments offered on each floor. He thought of the pains he was getting from his scar and decided that if he was in a hospital, he should get it checked. When Mr. Weasley upset Mrs Weasley by letting her know that they had tried to stitch his wounds closed, all the children present found a reason to leave the ward. Harry took that opportunity to walk up to the fourth floor, which he remembered being the spell damage treatment floor.
Here he asked to see a healer in connection with an old injury. The healer who came out was a young person and after listening to his concern, examined him, then asked Harry's permission to call in another healer. This one was a native American from Canada, he examined Harry's scar and after a short talk with the first healer left the room. The original Healer then told Harry that although the problem was serious, they could cure him, and the other Healer had gone to contact a specialist. However, as the specialist lived in Canada, it would take a while for him to reach London, and could Harry spend the night in the hospital. Harry agreed to spend the night, once a message could be sent to the Weasleys.
Harry then asked what was the problem with his scar. He was told that it appeared to be a partial possession by another wizard. Harry got worried, as it could only be one wizard. He understood the need for urgency in treatment, and wondered to himself why no one had checked on the scar before.
By the next night the scar was treated, and he and the Healer agreed to an excuse that could be used to satisfy all queries as to why he needed treating, as Harry preferred to keep the true reason secret as long as possible. For the rest of the Christmas holidays Harry had restful nights, with no visions or headaches to worry him. With only a few nights to go, before Hogwarts reopened, the Headmaster visited, and told Harry about his theory of Voldemort performing legilmency on him, and the need for Harry to learn Oclumency, and that Snape could teach this to him. Harry asked him to explain how legilmency and oclumency work. When they were explained to him, he laughed, as he stated that since he was nowhere near to Voldemort, how could a spell which required eye contact be used on him, Dumbledore then explained that it was the after effects of the failed murder attempt from 1981, which left them connected. Harry then asked how could learning a a protection to an eye based spell, protect him from something which was not eye based, were there no other options? Dumbledore again explained that oclumency protected the mind and any attempt at mind influence could thus be protected. Harry looked at him and laughed at him. Dumbledore was shocked. Harry then stated that there was a a non-Snape solution that he preferred to try, go and get the scar examined by a Healer and any after effects removed. He then added that he had already implemented that solution and it worked, as he had no dreams about Voldemort since doing it. Dumbledore was upset, as this threw a number of his plans awry. Harry saw that he was upset and wondered what plans he had upset. He decided to be brave and asked the headmaster why he had not been treated before, or why treatment was not the first option now, rather than Snape. Dumbledore told him that he could not tell him at this point. Harry then asked him to tell Sirius, who would then tell him only that the reason was logical or not. Dumbledore again refused. Harry made up his mind at that moment that he was leaving Hogwarts and Britain as neither the muggle or magical side was looking after his interests.