It is normal for POP signs/symptoms to come and go, tissues will bulge out and then recede, also when you are lying flat on the table for pelvic exam the organs can shift back into their normal positions making the POP flags less obvious. Many gyns do not catch it. When you are involved in activities that create pressure on pelvic cavity (even downward pressure from coughing/constipation), it makes POP worse. Below is a link to article on POP basics I posted to forum-
Ultrasound is not a typical test for POP, it may or may not show up depending on what they take pics of and what kind(s) of POP you have. Urogyn will be able to tell w/o test whether or not you have POP but will probably have a couple of tests done to fine tune diagnosis/degree.
Please do not feel alone, there are millions of women in the US with this and millions more women around the world suffering with it as well. Truly time to create some awareness, it's been in the closet for way too long.
I'll send you a PM on urogyn in your area later today, have to hit the road right now so hang in there a bit longer!