Dear parent
How old is your child? Is she more than 8 yrs old? She might be suffering from social anxiety. In children it manifests as shyness,clinging,awkwardness with strangers and at gatherings etc.
Next Steps
Give attention to her stomach problems only if legitimate. Be firm and set her school routine as early as possible. However don't punish or force her to talk to strangers,make friends etc.Give one task at a time.Eg. you have to say hi or hey to the erson you meet and then take their leave.Gradually the script can be added. Likewise you can agree to meet her during school at say every 1.5 hr intervals. but if she comes seeking you she will miss 1 meeting and wait for next on schedule.
Health Tips
if your daughter is 12 yrs she canbe started on some medicines.