It is important to know what chemotherapy
was given to you and also the pathological diagnosis of the cancer you have suffered from. Anyway, as you mention breast cancer
probably it is infiltrating duct cancer as this is the common diagnosis. It is not clear from your question whether any surgery was done or not, are you put on any hormonal
therapy or not. These issues will be dealt by your consultant oncologist
. Your present problem is repeated blockage of right ear and feeling of presence of fluid in it. This complaint is not related to your malignant disease process. It may be due to secretory otitis
media. Middle ear inflation with or without antibiotics may be an options. consult with your otorhinolaryngologist.