1. It may be happened by direct sunlighting. 2. It can be got by biting of mosquitos. 3. It may be got by leading neatless life. 4. Using clothes more than one week. 5. Not using quality soaps.
Getting hit can cause this because you bleed internally and when this happens you see it but it doesn't come out which will look red. Many people don't know that our blood is blue.
