Any vet techs or vet experienced?

Bailey • Ava Madeline🧸 07/23/2020🌈 IVF baby

I just noticed this on my dog this morning.

I know he didn’t have it a few days ago. Should I take him in or see if it clears?

Ignore his dirty hair he is a messy boy.

Update: he’s going to the vet tomorrow morning thank you everyone !