I'm pretty sure there's more symptoms to a Pulmonary Embolism than what you seem to be describing. www.mayoclinic.org/diseases-conditions/pulmonary-embolism/basics/symptoms/con-20022849
This page specifically addresses Flank Pain, see if any of the listed causes here might be a contributing factor. paininleft.com/flank-pain-left-side/
You're pretty well covered by Doctors examinations. If they thought a Pulmonary Embolism was the cause, they'd taken immediate action. Make sure to keep your follow up visits and report new or worsening symptoms to your doctor. If you had procedures involving your Kidney, perhaps the sensation is from that, and you mentioned your lung as well, again, perhaps residual irritation from that.