Hey there, @
sheilaannmarks. Could you please go further into detail as to how they're hacking things?
Your son (or even you) may have downloaded something called a "RAT" or a keylogger; a virus, if you will.
If not, his emails could have been "hacked" by him having a bad security question that anyone could have answered for him. If that happened and he used the same email for his Facebook/accounts in general, said hacker could have just reset all of the passwords and changed them to their liking.
With the information provided, that's all I can really say until you go further into detail.
I suggest that you & your son read some threads in the Anonymity forum which can be found here:
http://www.hackcommunity.com/Forum-Anonymity
Or you can even check out my Anti-Dox'ing handbook, which can be found here:
http://www.hackcommunity.com/Thread-Tuto...x-Handbook
I would highly recommended that you read my handbook, not just because it's my work. This is something that I think EVERYONE needs to know about if they give a damn about their security/privacy in the cyber-world.
EDIT: I just figured that I should add in that I'll help you beyond the use of just this forum if you're willing to actually discuss your issues with us. And are you communicating through the potentially infected system right now, or a different one?