Sorry you are having it hard,
I am making assumptions from the little info you gave. ESA is for a limited time and after that you are expected to go onto JSA. I don't know if you have a partner and if so their status, how many children and what age, if you are getting other benefits etc etc.
Therefore it's hard to give a precise answer, however, those who are supposed to go from ESA to JSA usually face the same problem that often JSA can't be claimed if you have a sick note from your Doctor saying you are not fit, it's all a bit mixed up and you really need to contact your nearest CAB and get assessed and appropriate advice, also this may help put your mind at rest.