Suffocating and sweating

Have any of u experienced this while doing ur session?

I was hitting the right spot with my toy yesterday (voluntary), the feeling that u have in ur dick when u about to cum was intensifying, my dick got a little hard as well. Then suddenly my chest got heavier, it was really hard to catch a breath and i started sweating. It lasted about 10s I guess but it surely caught me off guard.

How do u get those involuntaries contractions tho? Cause all my sessions I was moving the toy voluntary and Im not sure if i should stop and do nothing or keep doing it voluntary and someday the involuntaries will happen. What do u think?