Just a little something to try over the counter for the time being. As PC muscles engaged, even though you don't actively do kegel exercises, think of it as kegel muscles being strains due to the amount of other surround muscles tissues are engaging, forcing the PC muscles to counterbalance. DLD is correct to say to work on the PC muscles just a bit more. However, you can also relax it during the time over engagement using magnesium. Magnesium is supplement to relax the muscles from too much stresses and fatigues. I drink it after a long day of over exerting my muscles, while some less active muscles cause me spasms in the middle of the night causing restlessness.
The secondary portion to that is to also create a balance of kegel and reverse kegel counter part. Don't just actively do kegel without providing a reserve kegel period. While sitting and resting, I bare down on my PC to force my muscle to relax. While I walk, perform active PC exercises, or the body naturally engage kegel activities such as erection, the body strengthen the PC during this period. Once again, force your PC to relax through reverse kegel.