First step will be to ascertain the most probable cause of forgetfulness. After finding the most probable cause, we will proceed to concerned speciality.
If it's due to
Vitamin B12 deficiency, then we have to visit general physician - internal medicine.
If it's due to vascular insufficiency to cerebral cortex, then you have to visit neurologist.
If it's simply due to stress, you can go ahead with Homeopathic Medicines or psychiatrist.
Next Steps
Take nutritious diet including more fruits and vegetables without peeling, take plenty of fluids, take 8 to 7 hours sound sleep. exercise regularly.