Dear
Welcome to HCM
We understand your concerns
I went through your details.
Autism spectrum disorders are definitely troublesome for children as well as care takers. In order to change or eliminate a behavior, such as fecal smearing, it is important to first understand the function of the behavior. There is a reason your child is engaging in this behavior, so understanding the motivation behind it will best inform the type of intervention/s to employ.
I suggest you to go through many articles available across the internet, understand autism, understand your child and then slowly move forward with corrective measures. I suggest the following web link. Take care.
http://nspt4kids.com/parenting/help-reduce-fecal-smearing-children-autism/
If you require more of my help in this aspect, please use this URL. http://goo.gl/aYW2pR.
Make sure that you include every minute details possible.
Hope this answers your query. Available for further clarifications.
Good luck.