I have a boil on top part of vagina rite under belly could this be caused by that i have a slight cold?

Not directly: Your illness can make you more susceptible to other illnesses.

Probably not: If what you have is really a "boil", then it's a skin infection, and that is usually caused by a bacteria. Most upper respiratory infections are caused by viruses. So it's unlikely related, except that if you are run down, and tired, your immune system is weaker, and you are more prone to infections in general.