The numbness you are having can have all kinds of different causes, as it is a symptom of many different diseases.The complaints you have described suggests that there may be some pressure on or damage to that nerve where it emerges from the spinal column supplying the foot. Other possibilities are:high blood pressure, diabetes, multiple sclerosis,stroke,transient ischemic attack.Also this can be due to :Underactive thyroid,abnormal levels of calcium, potassium, or sodium in your body,lack of vitamin B12,certain medications,
The underlying cause of numbness or tingling should be identified and then treated by your doctor.Tests like electromyography and nerve conduction studies,certain blood tests,electro physiological studies are required to make the exact diagnosis.I suggest you to make an appointment with a neurologist to know the exact cause & hence its treatment.
Alcohol is not directly related with numbness,but it can aggrevate certain conditions which can cause numbness.Yes,high blood pressure may cause numbness.You need a checkup from your doctor.The underlying cause of numbness or tingling should be identified and then treated by your doctor.I suggest you to make an appointment with a neurologist to know the exact cause & hence its treatment.
Hope my answers had helped.