Why does a person who has undergone surgery for SDH not regain consciousness and experiences seizures despite taking anti-seizure drugs?

Hello doctor,

Around 15 days back one of my known 81-year-old male got unconscious for hours. The doctors diagnosed him with FTP (Fetal type posterior Cerebral Artery) SDH (Sub Dural Hematoma) and they referred him to another hospital. He got operated there and the doctors said that the clot was removed, and his BP (Blood Pressure) was fluctuating but was later controlled. He also got a fever and cough. Tracheostomy was done and he was kept on a partial ventilator. In addition to this, they also kept part of his skull inside the abdomen on the day of surgery for some days. But that has now been attached back to the skull. He got seizures later that day. Right now the patient is not having a cough but seizures occur and he is on anti-seizure drugs. He is now unconscious for three days, not opening his eyes but his vitals are stable. The doctors have shifted him from ICU (Intensive care unit) to HDU (High dependency Unit) but I think he was showing better progress in ICU (Intensive care unit). The doctors are saying that his CT (Computed Tomography) scan is normal now. Please give me a suggestion on whether we should continue to let him get treated there or should we shift him to another hospital. Why is he unconscious? A few days back he was opening his eyes. Why is he getting seizures frequently?