First of all, keep in mind that I am unable to diagnose you because I am unable to examine you, this forum is for educational purposes.
Your body has about a 1 month supply of thiamine (vitamin B1) that is stored in muscle. It is a water soluble vitamin and deficiency usually results from decreased intake, decreased absorption or impaired metabolism. Within 1 week of low thiamine supply symptoms can develop a syndrome called beriberi with tachycardia, weakness and peripheral neuropathy (which causes pain, numbness, tingling in the arms and legs). At this point the symptoms are ususally very reversible and resolve completely with replacement (Thiamine 100mg per day (IV may be needed if absorption is a problem)). If the deficiency persist and the symptoms worsen patients develp wernickes encephalopathy with vomiting, fever, abnormal eye movements and altered mental status. This syndrome can then progress into a progressive worsening of mental status to a profound dementia called Korsakoff syndrome (at this point, permanent damage is done, but it is usually partially reversible with thiamine). The most common cause for thiamine deficiency is alcohol (alcoholics have poor dietary intake, decreased absorption and impaired metabolism due to liver disease). Other causes include short gut syndrome (due to bowel surgery, inflammatory bowel disease, gastric bypass etc), dialysis, cirrohsis of the liver, and improper diet (for example people living off of humanitarian aid rice have developed beriberi due to the lack of other micronutrients in their diet).
I hope this has been helpful.