Hello Sakshi
This is Dr Mittal
I will try to answer your query
However the clinical details are less in your query
I would have preferred if you had added any other symptoms as well
That would have helped know the type of infection
Therefore I am assuming you have no other symptoms except fever
ESR usually means that there is something going wrong.
High ESR is usually a sign of long standing problem, or even Tuberculosis
In fact tuberculosis is one of the main causes of fever with high ESR with evening rise of temperature
Without further details it is difficult to comment what it may be. Even viral infections can cause the issues.
Suggest to meet a physician, because in absence of other symptoms, the physical signs and features of examination become crucial.
Best of luck
Feel free to ask a follow up query
Dr Mittal