That yoga stretch.... I'm guessing that was a back extension? That IS a good position/stretch... I do that every morning and evening. It looks kinda like the 'cobra pose' (but don't go much above your elbows!).
I also do a great-feeling one that looks like the 'puppy dog' pose (get on hands n knees, then drop/rest your chest to the floor - keeping your sit-bones in the air.., make sure your femur bones are at a right angle to the floor, let gravity put traction on your lumbar spine... great stretch!)

If you read the indications/contraindications (warning labels) on any prescription medication, it can scare ya no matter what it is! Trust me! I've seen many that spooked me too. Pharmacist helped set me straight. I wouldn't worry too much about Celebrex for the short amount of time you'll use it though. If you want...try Aleve instead. (not that I'm a doctor - but one of mine told me once that it is just as good - and cheaper!). Aleve is naproxen sodium - a generic of naprosyn (anti-inflammitory). Good stuff, too! Orrr... good ol ibuprofen.. another good anti-inflam.

Unfortunately, I've had a lot of experience with a myriad of pain medications. And as I said...the really GREAT anti-inflammitory was my PT!

You're on the right track, Luna!