I am as relative newcomer, and have just started BCG myself, but something doesn't sound quite right. The usual protocol for BCG is 6 weekly instillations, followed up by 3 weeks maintenance, usually at reduced dose (at 3 month, 6 month, then every 6 months out to 3 years, or more) This is the protocol developed by Dr. Lamm, and sometimes also called the SW Oncology Group (SWOG) protocol. As others have said here, this BCG protocol is generally used for higher grade tumors, or in cases where there has been recurrence of low grade tumors; it's also used for CIS (carcinoma in situ).
It doesn't quite sound right that your Dad would have a single BCG instillation, followed by 6 more. The latest thinking on low grade initial papillary tumors is a single dose of a chemotherapeutic agent such as mitomycin after the tumor is removed, but not BCG. (Although I will say my own urologist did not do this when I had my first tumor 2 years ago, and has now started me on BCG for a recurrence -- 2 small tumors, low grade and non-invasive.) Is it possible your Dad has CIS? BCG might be used for that right away. I don't know much about CIS, but I believe it can look like a flat red inflamed area ("burned"). Another thought about the "burning" of his bladder could be an incorrectly mixed BCG (or other chemo) solution, where he got way too high a concentration. However, I believe some people can have a very strong reaction to even a normal dose of BCG, and if that's the case, the same therapeutic effect can be achieved by reducing the concentration way down (to even as low as 10%), but they won't (shouldn't) do any instillations so long as there is any infection of major irritation.
It definitely sounds as though you need more information, and certainly a second opinion. Best wishes to your Dad and your family.