What you are facing is a perceived memory disturbance and not the actual memory loss
. The fact that you could recall the information after some time suggests that its not the actual memory disturbance. The problem occurs when you are not attentive or are fatigued. Same may also occur if you are having anxiety
or worry cause of some concerns. Firstly please don't freak out yourself considering that you are suffering from very serious illness. These issues are treatable, but you need to see a approachable psychiatrist
who can assess you before he can start any treatment.
Hope I am able to solve your concerns,
have a nice day.