My son had tubes installed when he was 10 months and he had them for over three years. One finally fell out and then the other fell out about 6 months later. Before he had tubes, he had ear infections ALL of the time. Then, he didn't have any at all. But, just before the last tube came out, he had one last ear infection that just would not go away. He probably had it for 6 weeks and the doctor told me if the last round of antibiotics did not work, she was going to have to remove the tube because she thought that maybe the tube was holding the infection. She said that she would put him under because removing the tube can hurt.
Also, I have a friend whose daughter had her tubes removed and they did NOT put her under. He said that his daughter screamed like you would not believe and if he had to do it all over again, he would put her under.
Anyway, ours eventually did fall out and all has been well. The itching MIGHT be a sign that it is getting ready to fall out?