Where can I go for help? What are my options legally? I was assaulted by this man and held unlawfully for a $3 item? I need help

After purchasing $70 worth of groceries, I realized I had placed two small items meant for purchase in an outer coat pocket. I took the items back to the cashier, apologized, explained my mistake. I do all of my shopping Here and assume recognition. She took the items without incident. I was actively looking through my bags for the receipt as I was only given the coupon part. I was approached by a man who appeared to be homeless. Caucasian, oily uncut hair, unshaven, oversized black clothing, asking me to follow him. Behind him was a younger Hispanic male missing teeth, also dressed in all black. Finally the older male said "Loss Prevention" I apologized and willingly followed realizing my error and waited for the younger male to retrieve the items both had admitted to not seeing hand back to the cashier. The older male began to shut the office door. I asked him not to. He refused. Younger of 2 came back with items, I then stood to leave as the door was shut, locked, physically blocked while also standing in front of female associate. Accused of tampering with a peeler, I demanded the door be opened, i was placed in a headlock, legs kicked, face hit the floor shattering glasses.