From time to time my husband gets a welp or 2 on different areas of his back, shoulder, or chest, that are about a 1/2 to 1 inch in length and not very wide, and itches. Usually goes away in a day or two, sometimes less. This started about a year ago, with several of these on his back. They lasted several days, and all we could do to help relieve the itching was to soak a warm cloth in salt and lay it on his back. Now he gets just one or two of these, but not all the time. What is it?