Angle does make a difference. I can't sit in a booth at a restaurant because of the angle the booth forces me into. Instant pain.
I used to be a systems engineer, and sat at a computer 5+ days a week, often for 10 - 12 hours.
My tailbone was so sore, but nothing showed on x-rays or mri. No treatment available because what the heck would you be treating?
Then my company did me the supreme favor (I mean that!) of involuntary separation - medical included and a bit of a payoff for years of service.
So i didn't work for 10 months. Loved it. About 8 months into the off-time, I noticed that my tailbone didn't hurt any more. My guess is that I had a chronic bruise type injury and that getting off my duff was the cure.
I have fibro, so I'm sure that was a contributing factor. Now I notice that my hips get sore if I sit too long. Most likely osteo arthritis. So I don't sit too long any more. My pressing station is about 10' from my sewing machine, and I cut fabric at a 36 inch height craft table. The more I have to get up, the better off I am.
Best advice that i can give you is to see a dr.