my best friends 2 year old only grunts and uses single words.things like "ca" for car and no-no for nose. i've never heard her say more than 3-4 in her entire vocabulary. she avoids eye contact,picks at herself,bites her nails, has screaming fits multiple times a day that usually end in her vomiting because shes gets so worked up, she cant calm herself down. she doesn't answer to her name, or appear to even hear u talk to her, she's in her own litttle world. im worried. she also seems to have a biting fixation, she likes to bite, things and toys repeatdly, leaving them bitten up and disheveld. still enjoys her infant teething rings. she bites and pinches her mother repeatdly. and doesn't seem to be all that interested in toys, shes very distructive. Her mom thinks its all normal. im concerned, what do u think?