Answer: Epilepsy.
Explanation:
Epilepsy is a brain disorder characterized by repeated seizures, it occurs when there is an abnormal electrical discharge by the brain, this leads to a change in the behaviour of the victim without the victim been aware of the happenings.
Abnormal electrical discharge is caused as a result of certain drugs, fever, brain injury, infection and shortage of oxygen to the brain, etc. For one can be diagnosed of epilepsy, such person must have had not less than two seizures.
Probably blood clots such as bruises.
That seems like something you would need to call the business you are seeking an appointment with on a daily basis, to find out if they've had any cancellations. Some businesses have ways to set appointments online, but not all of them do.
So its acquired immunity and the cells responsible are the B lymphocytes that produces antibodies against the virus. Memory is keep since first encounter of the virus by the immune system by way of the antibodies that was initially produced. The antibodies are there already, which makes it fast to act upon when expose again.