Not only can this be harmful, it can cause more problems. Attempting to reposition crystals without instruction from your health care provider can cause the crystals to be moved incorrectly. There have been instances where patients have given themselves a concussion during the process or damaged their eardrums from flushing liquid into their ears. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.