How did you know i did this just yesterday.
Cuz he's smart, lol.

As, Eman, noted, it never hurts until we stop. Once you're feeling better, start back s-l-o-w-l-y increasing time and distance in small increments.
I found it painful to sit for long periods of time also. For months! The car was the worst, due to the confined space, seat belt position and inability to stretch much. Just as, myglasshalffull, noted it felt like I was sitting on a tennis ball, but I always described it as "the firmness of a tennis ball, the size of a golf ball." You can try sitting on a flatter ice gel pack and see if brings any relief, while forced to sit for longer periods of time.
I wish you the best...let us know how it goes.