Hi Bella,
I assume you are refering to the PC muscle. The sling muscle that keeps your lower intestine, bladder and other organs in place.
That being the case, depending on the type of exercise you are doing at the gym may have a direct bearing on thightening that muscle, and subsequent restriction of your vagina.
Without knowing a great deal more of your actual situation, you may find relief by returning to a more regular dilation routine. This would specifically target the muscles and tendons closely associated to vaginal area.
Speak to you as soon as I finish a cup of tea.
Huggs
Catherine