Thanks for your question on Healthcare Magic. I can understand your concern. You might be having vaso vagal syncope. It is parasympathetic response of the body. It is not pathological. It is normal for some individuals. Affected individuals get fainting attacks while doing specific actions like seeing blood, sudden dark or excessive light etc. In your case menicure and dental procedures are provocating factors. Only cure is drinking too much fluids before these procedures. Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.