What is the difference between these two? How is PID diagnosed and treated?

Just trying to go over possibilities in my head of what I've been dealing with for the past year and a half. I've been told BV by numerous docs, but no tests confirm that. Nothing ever grows out on cultures, I just show lots of white blood cells. I've been on tons of antibiotics and nothing works. I have a constant sour smelling white/light yellow milky discharge.

Would a vaginal ultrasound be able to show the difference between the two? About 7 months into the infection (on month 16 now) I had one done and that Dr. said there was inflammation, but still said BV? Should I go get another?