Pencil chewing

My daughter is nearly 8 and up until a few weeks ago sucked her middle and ring finger frequently. After many failed attempts she seems to have successfully stopped. She has always done it but until grade 1 it was mostly at home, as school became more difficult we noticed the finger sucking increasing. She has now stopped it but chews all her pencils at school, in fact most things go in her mouth. I am constantly replacing her pencils. She says that she doesn't realize she is doing it. She is getting teased quite badly at school and her peers are alienating her from the group. She also struggles academically, particularly with Maths.

She is now refusing to go to school and our once carefree daughter seems anxious, confused and sad. Is this an SPD issue and should I take her to an OT. Any suggestions for the oral fixation? I don't want to give her an aid to chew as I think this will enhance the teasing are there any discreet alternatives?