The actor was taken into hospital recently to have surgery, which he said was related to his accident on set in the 1982 film Coolie.
Bachchan told readers of his blog: "I seek forgiveness... I will not be detailing any more. Some fresh medical issues have come up, and I need to concentrate on the treatment now."
Earlier in the week, the 69-year-old Bollywood legend wrote: "The morning has been nightmarish. There has been incredible pain in the region of the surgery, and the spasms so acute that they brought me to the level of a scream which is saying a lot, for my resistance to pain has been quite satisfactory in the past.
"But the doctors were immediately summoned and after change in the dressings and pain killers, there seems to be now some semblance of relief. Not entirely, but entire enough."
In September, Bachchan suffered a minor chest injury on the set of Ram Gopal Varma's Department.