I am sorry to hear about your friend's speech difficulties. I would agree with Martin, @predictable when he suggests a consult with a good neurologist. I would add to that a consult with an otolaryngologist (an ENT who specializes in the vocal cords) who can check out the vocal cords, throat, etc.
I'm wondering, however, did these speech problems come on suddenly or have they been over an extended period of time? Has she had any other problems such as balance, gait, walking, using her hands, etc.? Any headaches or dizziness? Any extreme stressors?
A speech therapist might be very helpful to your friend. I would encourage her to keep looking for an answer. Will you post again and let me know how she is doing?