Hello - I am unclear what is going on here and from this picture alone, am struggling even to sex your dog with absolute certainty, although photographs can often be tricky and that may not be the same in normal life. As you cannot decide how urgent the case is, it would make sense to call the emergency vet and to ask them to triage this case. Triage is the act of figuring out formally how urgently a patient needs to be seen. I hope that you get to the bottom of this and would be keen to discover what was found out.
On reflection, my best guess is that your dog is male and the lumps therefore testicles but if they do not look normal to you for your dog, then we would absolutely reccommend explaining this to your vet on triage - vets talk about personal bits all the time and will appreciate directness.
Thank you for confirming that. To be honest, it would normally be obvious from that angle; it is only unclear in this case because of the changes to the anatomy. Female dogs can get a condition known as a perinneal hernia, which is much more commonly associated with male dogs, where the abdominal contents push backwards through the muscle around the bottom until the are protruding in a lump onto that area. It is not usually a desperate emergency unless a loop of bowel etc gets through the muscle or something twists, whereupon it can become an emergency very quickly. Cancers (benign or unpleasant) can also form there as lumps. Fluid can collect - although it would be an odd place and there would have to be some reason for it - a cyst would be the most benign possibility that I can think of. Definitely speak to your vets about triage and please do let us know what they find.