Trojan generic activity popping up constantly

Hello. I have been getting the following Norton pop up box "Norton blocked an attack by system infected: trojan.generic.activity.2" The box will appear repeatedly, sometimes every few seconds. Additionally, I recently experienced an attack on my instagram account. I believe my e-mail was accessed too. I know the person behind this, but I have no proof, and they are attempting to compromise my job and work relationships. I have begun to change my accounts passwords, but if they are truly determined to damage my reputation, what can I do?

I realize that the Trojan message and the hacking of my information may not be related but any help and advice I receive would be greatly appreciated.