The yellowish gel and bloody tissue you are seeing is likely shedding lining and mucus from your bladder, which is healing after intense BCG-induced inflammation and prolonged catheterization. This is a normal part of the recovery process and typically does not lead to long-term complications. The pain should gradually resolve over the next few weeks as your bladder lining regenerates. To aid healing, drink plenty of water. However, please contact your urologist immediately if you develop a fever, worsening pain, or find it difficult to urinate, as these signs require evaluation to ensure a safe recovery.