I have had numbness in my left little finger for almost 2 months.. my mother had multiple copies sclerosis. is there any link? what is could it be?

Check the elbow 1st: While multiple sclerosis can certainly cause focal numbness like you describe, ulnar neuropathy (usually a pinched nerve at the elbow) is a much more common cause, especially if the numbness is made worse by certain postions of the arm (for example, propping the elbow on a table or car window). Try avoiding elbow pressure for a few days- a neurologist can help confirm this if things don't improve.

Cubital tunnel: I agree that irritation of the ulnar nerve is a much more common cause of numbess of the small finger. The most likely site of compression is at the elbow but other areas could be involved. Typically the pain is worsened by flexion at the elbow, and sometimes the pain noted more at night, even causing waking.

Ulnar nerve: Likely due to peripheral nerve problem at elbow or wrist, and not a sign of MS. The chance of you having MS at this point is well below 3-4% and you can get answer via an EMG study.

The small finger is: innervated by the ulnar nerve, this nerve can be compressed from the upper arm down to the wrist in several locations. Other areas of nerve compression include the neck and the lower cervical nerve roots. See you PCP and get evaluated and examined as these problems are common. MS is one neurological issue but don't assume this is what you have