You should be under care of a neurologist at this time. Encephalitis is a swelling of the brain where the swelling actually causes pressure against the skull. There are different causes, oftentimes viral but can be bacterial.
What tests has the doctor done and what did he find thus far, to make the diagnosis of encephalitis?
Are you having any other symptoms such as stiff neck, lethargy or feeling confused.
When you say relapse, I think you are referring to the headaches and nausea.
I can't determine that this is the correct diagnosis based on your symptoms but I think you need medical attention right away. This has been lingering for too long and you are not getting better and do not seem to be on any medication or treatment besides bedrest.
Call the local hospital and ask for a physician rederral to a neurologist who is highly ranked at the hospital. Make an appointment as soon as possible.
I hope all will be well with you!