does this happen consistently through out all types of walk you take or is it only in the morning? do you do some kind of exercise before you start walking? have you had similar conditions in the past at some other time in the past? do you have any other medical conditions, such as diabetes or cervical spondylosis?
i think you should get yourself examined by your doctor to rule out any injuries/trauma. there may or may not be any major cause but its better to be sure.
Thumb falling asleep suggests a nerve impingement either at the wrist or elbow or even at the neck. I would suggest you to schedule an appointment with a doctor for a complete clinical evaluation. At the same time you can start with a B complex supplement.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. Med Help International, Inc. is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.