Yellowish pus from Nitro's PP

[Hoehoe]

Hi people,
Nitro's got a problem recently. There is this yellowish pus like liquid thats coming out from his "little PP". Its something thats happened before but just recently its just getting too frequent. Its staining the beds and sofas but i'm more worried about his health status. Is this normal for a male dog or is this a symptom to some hidden health problem? He's acting quite normally and does not show any strange behaviour like excessive licking of that area. Nevertheless we are still gonna schedule a vet visit soon but just want to find out if anyone face the same problem before.

Thanks!
KH.