I have had numbness and tingling in left thumb and index finger for 5 weeks now. it sometimes aches in the hand and up to the underarm what is it?

Nerve impingement: Carpal tunnel syndrome is likely. A hand surgeon is best qualified to evaluate and treat you. Often a corticosteroid injection and wearing a wrist brace improves the problem. Surgery may be needed,however.

Pinched nerve. : U need a work up to discover its location,cause,and the best treatment.

Check it out : Sounds like. A pinched nerve. It's NSAID s may help. Check it out with yur doc

Nerve issue likely: Sounds like a nerve impingement, the most common one being carpal tunnel syndrome but as pain goes up into armpit, may be higher up in neck as well, consider an EMG/NCV study. Also look to make sure you have no cuts on that arm and the this is not an infection with a swollen gland in your armpit.

Pinched nerve: You are experiencing nerve irritation called radiculopathy. Most commonly, one of the nerves coming off of your spinal cord in your neck is getting pinched or irritated for some reason. You definitely need to be evaluated in person. Waiting too long could lead to permanent weakness in the hand. Treatment could be as easy as an Rx, but you might need an MRI. Please see a doc.

Cervical radiculitis: Pressure on the nerve which connects your spinal cord to the radial side of your hand by way of passing between two bones in your neck, then through muscles in the neck + shoulder+down the arm. Pressure or bruising of the nerve can be anywhere along there, most often involving bone spurs or bulging discs in the neck. A neurologist will help you. Avoid anything which involves twisting the neck.

Sounds like overuse: Do you do repetitive movements with your hands--computer use, texting, and or playing games on a console or phone? Any injuries or pain in your neck? It could be a compression syndrome such as carpal tunnel syndrome. Tendonitis may cause it. Peripheral neuropathy from Diabetes, multiple sclerosis. Rheumatoid arthritis can present with these symptoms as well.

Suggests: Likely nerve compression at wrist, and your description suggests this may be carpal tunnel syndrome. Have your doctor evaluate this.