Hi I Got A Hamster 2days Ago And I Sometimes

Hi I got a hamster 2days ago and I sometimes pet him/her ( I'm not sure if its a girl or boy) it seemed like a baby and it groomed nearby its ears, stomach , and the back. I just thought he/she is just grooming but I just saw that he/she chewed(?) his/her stomach and I am so worried and I hope yiu can reply my answer doctor please and thank you. I am so worried