Pain in tailbone. Relief right now?

I am experiencing pain in my tailbone area, right at the start of it, but the pain feels more intense on the left side. I am unable to sit on my left side, although I can walk without difficulty. Now, the pain has started to throb as well. If I touch the center of my tailbone, it hurts a lot. I work from home and sit on a chair for 10–12 hours daily, though I use an ergonomic cushion. A few days ago, I lifted some pieces of plywood, but they were not heavy as such. Since then, I have been feeling significant pain in my tailbone, and now the throbbing has started too. I’m unsure whether this pain is due to lifting the plywood, my prolonged desk job, or something else. Could you please advise what this might be and what I can do for quick relief right now?