As in your experience, pain is not a key symptom in primary (first) episodes of carpal tunnel syndrome. Instead, numbness seems to be more common after the surgery is performed. The presence of scar tissue around the median nerve and nearby soft tissue structures after surgery may explain the new pain feature. Loss of blood supply to those areas because of scar tissue pressing and blocking the nerve may be part of the picture.
Studies show that most people who have persistent symptoms after a first carpal tunnel surgery do get pain relief with the revision surgery. Experts in this area recommend entering the carpal tunnel away from the nerve to reduce the risk of complications from the second surgery.
The second surgical incision is usually longer than the first to give the surgeon more room to operate around the involved nerve (and avoid inadvertently cutting tiny branches off the main nerve). Coming in from the side of the nerve also gives the surgeon the opportunity to look over the area and find a pathway to the nerve that will not damage other structures.
The surgeon may need to relase some of the soft tissue structures over the nerve and retract (pull away) the bundle of nerves and blood vessels in that area (to avoid further injury caused by the surgical procedure). Each surgeon has his or her own preferred techniques based on experience and evidence-based outcomes from other patients and previously published studies.
You may want to ask your surgeon this question. Having an idea of the intended procedure may be very helpful to you. And it will give your surgeon another chance to think through your particular case and what is best for you.