French Internship Visa Question : PLEASE HELP ! (Paris)

Hello InterNations Paris!

I am in desperate need of some friendly advice. It is my hope that perhaps one of you might be able to shed some light on my situation:

I have an Italian student visa good until this October Protected content finished an MBA program in Italy). I have been offered a paid internship in Paris, for a period of 3 months, which I must do to conclude my studies. It begins the 18th of July.

Am I able to complete the internship (getting paid and all) while holding the Italian visa and my US passport, or must I get a specific French Visa? And if I get a French Visa, what kind and is there any way to get it without returning to the States?

Any advice or information would be incredibly appreciated. I am having so much trouble finding useful information concerning my situation.

Thank you and have a very Happy 14th of July week!