Rae
If the last Decision that you had for ESA was a Fit for Work one then you can only make a new claim for ESA if you have a new condition or your existing pones have deteriorated such that you would now qualify for an award. So you need to speak to your GP about the Fit Note that they will need to issue and yo made need their assistance with completing any documentation that the DWP send you about this issue specifically.
Our ESA Claim guides are on the following link.
www.benefitsandwork.co.uk/help-for-claimants/esa1 If you have further questions then please reply to this post and we will do our best to help.
Gordon