The bottom line: Unless it’s a condition you’ve had before, it’s nearly impossible to diagnose yourself; (. the same problem can have a variety of appearances because everyone’s skin is different). “It’s even tough sometimes for a dermatologist to tell what it is just by looking at it,” Dr. Mudgil admits. So whatever you do, don’t act rashly (pun intended) and do a Google image search to figure out what is on your skin. It’s more likely to cause anxiety than an honest assessment.