Trackpad Issues

Hi

I have an early 2011 Macbook Pro bought Last year. Few weeks ago my trackpad began behaving strangely not responding correctly and having a mind of its own. After a couple of hours I worked out it only acted this way when I had my power cable plugged into it. I researched this problem and found that it could be the battery swelling and and pushing on the trackpad causing it to malfunction. So I bought a new battery and replaced it and it seemed to solve it. However I wake up today and now the problem has returned, the only thing I can think of is the the power cable itself is the problem? Is there anything I'm missing before I buy a replacement cable?

Thanks

V