What's your profile ? Age, sex, distribution of body fat ? General state of health ? Has your weight changed recently ? Are you otherwise healthy ? Do you feel well ? All these factors are important before deciding you are unhealthy or " normally skinny ".
Body Mass Index ( BMI = weight in kilograms / height in metres squared ) gives an approximate guide, but there are exceptions :
< 18.5 underweight
18.5 - 25 desirable weight
25 - 30 overweight
30 - 40 obese
>40 extreme / morbid obesity
Vitamins are not the answer ! A balanced diet and regular exercise is the way to achieve desirable weight, whether the initial problem is malnourishment or obesity. That may be easier said than done, depending on circumstances. Obesity is the main problem in the UK - although malnourishment may be a factor in hospital inpatients and certain illnesses. Both malnourishment and obesity are problems in the Philippines, where around 4 million children are malnourished, and 2 million over-nourished or obese.
With so little information to go on, a forum such as this can't really help you further.
