This was my immediate thought too.

OP - it’s not that uncommon, and is totally treatable.

It’s just some muscles involuntary tensing up as a result of something going inside (or sometimes even the idea). Unfortunately, because it’s an involuntary reflex, you can’t “just relax” it away. It’s just something your body needs to unlearn.

Talk to your doctor, follow their advice.

For what it’s worth, both of the people I knew who had it when they were younger, once it was sorted, it stayed sorted.