"I replaced the rubber rim strip with Velox adhesive cloth tape"

I went through this problem 2 months ago and the above fixed it for me. The old rim tape was not adhesive and would shift when I put a tube in and mounted the tire. After a couple of weeks of flats after hitting deeper road cracks and then getting a subsequent flat I went with the Velox adhesive tape (and a little wider one) and there have been absolutely no problems. I suspect the tube was getting pinched on an exposed spoke hole.