There are a lot of ways discomfort can come into the picture. If you have narrowed it down to your cervix, though, different positions with different angles might work (try less deep positions, as well).
The cervix also retreats into a more comfortable position during arousal. You could try having a good orgasm before penetration, or get checked by a doctor if it's continuing to be uncomfortable. Cervical prolapse can happen after pregnancies, or something else could be at work.