Your dog can have anal sac problem. This organ is present in the form of a pair surrounded by rectum. It secretes brown liquid having bad odor but that is normal. The problem occurs when its muscles do not squeeze against hard feces and do not discharge. So these secretions keep on building up in the anal sac and creates different problem. If this is just brown liquid getting out of it then it is normal but if there other signs indicating some alarming situation then consult a vet soon.
It's probably diarrhea take him to vet if it doesn't get better
Diarrhea, no it don't need to go to the vet if it is that.
Well it's not exactly normal. You might want to give your vet a call and discuss it with them if it has just started. If it sounds like just an upset tummy or maybe a short term bug after getting all the details from you, they can give you some tips on trying to clear it up before having to go in and let you know when you should go in. If it's been three days with no other symptoms then you should go in and sooner than three days with other symptoms. Hope your baby is feeling better soon.
That usually means she is in heat. Dogs go through "periods" as humans do, and the most effective way to stop them, is to get the female fixed or spayed.