Have you been to a dermatologist? They can take scrapings of your skin and look at it under a microscope to find out what is giving you these symptoms. Some of the symptoms you speak of would not make sense as far as parasites would go..but it may be something else entirely that just feels like parasites. There are many conditions that give the sufferer the feeling of bugs crawling on and under your skin. A dermatologist would be able to help.
Hope you feel better soon,