Try to think back of the first time you had pain during intercourse. What happened in the period before? Some common causes:
Relational problems.
A vaginal infection, vulvar vestibulitis or vaginal dryness which makes intercourse painful. Even after the physical problem is solved you might still expect pain, leading to a vaginistic response.
Sexual abuse.
An operation, like hysterectomy, or difficult delivery of a baby.

If you find out what caused it, you should solve that problem first. Wait with intercourse, making love in other ways (kissing, hugging and satisfying each other manually or orally). Then go through the steps as described under ‘solving primary vaginismus.’ If you cannot solve the problem that preceded the secondary vaginismus on your own seek help from a gynaecologist, a sexologist or a relation therapist.