It sounds like you would be an ideal candidate to have laser removal. Mine was a huge hit.
Perfect result, two quick relatively pain free laser sessions on the area, cost about £250 gone for good.
I suggest you contact The Royal Free Private Skin Clinic through their website, as to which laser they use. I had it done in...
You need to go straight to a properly qualified dermatologist (Bangkok must have one!) and get an opinion.
I have had a BN removed VERY successfully by a Laser clinic at the Royal Free Hospital's Private Dermatology Practice, London UK. I had the mark over my shoulder blade since it appeared after a good Australian sun burning in...