Hi.. Thanks for the query.. Well, numbing of mouth along with nasty taste can be due to excessive alcohol intake that might be causing toxic side effects.. Other causes can be allergic to any specific foods, medicine side effects, metal toxicity etc.. Many a times transient ischemic attack can also represent with such symptoms but is accompanied by other symptoms too.. Therefore, in order to confirm the cause consult an Oral Physician and get evaluated and if needed appropriate referral will be done to Physician, Allergist as per suspected cause.. As of now avoid alcohol intake as much as possible.. Take Vitamin B complex supplements.. Hope this information helps.. Regards..