What Signs Should I Look For To Ensure My Infant Is Okay After Being Stepped On By An Older Child?

My 3 year old almost 4 stepped on my 7week old baby on his stomach/rib area the baby cried for a few seconds but settled down after a minute or 2 me and my mother in law checked for broken ribs and didn’t feel anything out of the ordinary and the baby wasn’t crying while we checked him we also checked his heart and his breathing it’s a little fast but we assume that’s normal in babies I’m just worried that there could be something wrong internally I’m really scared I want to take him in but he seems to be doing fine I think it’s just my anxiety I would really love to know what to look for incase something is wrong