Talktalk Email Account Hacked - sent emails sending again with suspicious link and originating addre

This is causing me such stress! As of yesterday, emails from my sent folder are being re-sent but from randon email addresses with a PDF link (obviously dodgy). I have had calls and emails from so many people saying that I have emailed them. I changed my Talktalk password and ran serveral scans . No problems found on my PC and the emails are still sending, even repeating.( nothing in my sent flder)  I guess that someone has got hold of my sent folder and is using it to spread malicious links. Any help very gratefully received. I s this a Talk talk wide problem? Please keep in touch if you get any news or a solution Simon