Tailbone, low back pain AFTER practice

I have a general question about pain encountered the day AFTER a particular yoga routine (not during the practice). I realize you can’t offer medical advice and will speak about this with my doctor when I next see him. But I would like input about whether it’s advisable to continue doing a routine if there is pain the next day (and sometimes 2-3 days afterwards).

I am 65 years old with occasional lower back pain (mostly early morning or late evening after too much couch time). I have some osteoarthritis but not severe. Generally, I find lower back relief from slow movements and stretches such as cat/cow. My specific question has to do with recent, rather sharp pain in muscles around the tailbone the day AFTER a yoga routine. This pain doesn’t occur during the class. The tailbone pain has been prevalent a couple of times after David’s “A 60-min Hatha Flow for Energy and Release.” I really enjoy this class (among his others), except I am generally unable to get into a cowface pose. I do my best to approach it but can’t get my legs to cross completely. Again, I don’t push myself too far and have not encountered sharp pain or discomfort during the class.

I’ve recently had a similar experience with a different area of pain (left buttock) after Rachel’s “Fundamental’s of Practice, Day 7,” which I’ve done several times in the past without any problems.

Thanks for any input you can provide!