He may need some really strong anti-emetic (nausea) meds. Phenergan is a great cheap medication for nausea. I'd stay away from reglan right now since it increases the wave-like motion of the digestive tract - including the stomach. Zofran, while incredibly effective at knocking out nausea, is also incredibly expensive. Your brother's GI doc may be the better person than the surgeon to treat any long-term nausea issues.
I agree with CalGal that time may be the only cure if the surgery was recently performed, along with diet changes and nausea and/or pain meds. The wrap may have been done too tightly, or adhesions may have formed making it even tighter. Whatever the problem, his symptoms are severe enough that he should consult both his gastro doc and surgeon.
He needs to go back to the doc that performed the surgery and discuss the problem. This form of surgery is not without side-effects. If the surgery has just been done, it may take some time to adjust and in some that adjustment period can be rough. But have him contact his surgeon or GI doc.