What can I do about this e-mail/spam issue? (See details)

This is a little complicated, so sorry for the long explanation!

Somehow my e-mail information has been compromised, and someone has been sending e-mails from a separate account pretending to be me. Only one person seems to have gotten one of these e-mail so far, though. The e-mails are also coming from a .edu account, which leads me to think it was my school e-mail address that was compromised (since there have been security issues in the past), but I have only e-mailed said person from my main gmail account. The accounts are POP3 linked so that my school e-mails are forwarded to my gmail, so that might have something to do with it.

A little over a week ago, I also got an e-mail that I had signed up for something that I had never even heard of, and it appears that someone else tried to use my e-mail address to sign up for this service. I immediately changed the passwords to the account and added security questions so that the person couldn’t get in, but the company’s customer service is terrible (EA Origins) and I am having trouble getting them to delete the account.

I have already changed the passwords and upped security on all of my e-mail accounts, but I guess the sender already had all the information they needed and the e-mails keep going out. I don’t want to delete my e-mail addresses, and since changing my passwords and increasing security didn’t seem to do anything, I’m not sure that deleting my accounts would even help the situation. My main e-mail account is a gmail, and I searched high and low for signs of being hacked (checked for other IP addresses, forwarding addresses, etc.) and I can’t find anything to show that this was the account that was compromised, which combined with the .edu sender and past security breaches, leads me to think it is my school e-mail was hacked- in this case, it’s not even possible for me to delete it, and I don’t know where to even begin with a Microsoft Outlook e-mail.

So essentially, I don’t know what I can do to tackle this problem, or if there is anything I can do about it at all, since it’s a remote e-mail account. I’m usually pretty good about this kind of thing and keeping my information private. Is there any way I can get the e-mail address closed, or is there anything else I can do about it? Thanks in advance!