Welcome to icliniq.com.
Thanks for sharing such a detailed information with us. I can understand your problem very well.
At your age memory disturbances are not usual, because dementia (the most common cause of memory loss) is very common in old age but at your age dementia is very rare. So, in your case, we have to proceed accordingly to rule out other causes as well.
Other causes at your age could be thyroid disturbances, diabetes, anemia (nutritional deficiencies), hypertension (increased blood pressure) and heart diseases (ruled out with your ECG). I think you have ruled out most of the physical causes by investigating, as you have mentioned that these tests were negative in your case.
Next issue which can cause memory loss at your age could be seizure disorder like absence seizure or other types of seizures. If you cannot afford an MRI scan, you can go for a cheaper option like CT scan/EEG to rule out seizures.
Another common cause for your memory loss (which is good to be called as cognitive disturbances) in your case could be due to either depression or anxiety (as you have mentioned above that you never feel refreshed after sleep, often feel tired, shaky hands, fainting, restlessness).
I would like to tell you other symptoms which can be suggestive of depressive disorder are low mood/sad mood, loss of interest in work, hopelessness, appetite disturbances, reduced concentration and attention; reduced self-esteem and self-confidence; ideas of guilt and unworthiness (even in a mild type of episode); bleak and pessimistic views of the future; ideas or acts of self-harm or suicide.
Symptoms suggestive of anxiety disorders are apprehension (worries about future misfortunes, feeling "on edge", difficulty in concentrating, etc.); motor tension (fidgeting, tension headaches, trembling, inability to relax); and autonomic overactivity (lightheadedness, sweating, tachycardia - increased heartbeat or tachypnoea - increased respiratory rate, epigastric discomfort, dizziness, dry mouth, etc.) in addition to the memory disturbances.
So, after getting all the necessary investigations like EEG/CT scan done, you can provide a more detailed history of your disease and we can make a particular diagnosis.
One more thing I would like to ask you is that, are you having some repeated thoughts in your mind which you fail to resist or are you more conscious about dirt? Do you keep checking the locks? These are the symptoms of OCD (Obsessive Compulsive Disorder) which also can be presented with forgetfulness sometimes.
If all the investigations are normal, then you can start pharmacological as well as non-pharmacological methods of treatment for depression and anxiety. You can use some relaxation techniques like breathing exercises, yoga therapy for anxiety symptoms. There are many safe drugs available for early and good recovery, but you have to be sure about your diagnosis first.
You can start SSRIs (Selective Serotonin Reuptake Inhibitors) in low doses and increase them slowly and your problem will resolve definitely.
Revert back with the reports to a psychiatrist online -->https://www.icliniq.com/ask-a-doctor-online/psychiatrist