Endometriosis? When to see a doctor?

​I had painful periods when I first started getting AF and my dr put me on BC when I was about 16. 10 years later and I've been off BC for 4 months. The pain has return and it keeps me from completing my normal tasks. I've also always had pain - mainly when I'm on top - during intercourse. I did have this checked out with an ultrasound a few years ago and they didn't find anything. When should you see a doctor? I'm worried it could cause infertility issues but don't want it seem like I'm overreacting.