Very scared!!

I was walking my 8 week old French bull dog on the sidewalk when i noticed he had something in his mouth. I immediately grabbed it out, it was either a piece of hard plastic or glass, about the size of a fingernail. I’m pretty careful about watching him on walks but I noticed there were pieces of this stuff everywhere we were walking. I’m just scared he ate a piece without me knowing. He’s acting completely normal and ate his dinner, I did the milk-soaked cotton ball trick as well – is there any way I can tell if he’s ingested this glass or plastic right now? I know i will eventually be checking his stool but i’m very anxious and would like to know immediately.