Have had three vaginal deliveries one being 6 months ago. pain in lower abdomen during and after sex. no bleeding. is this normal?

It can be: Some women experience cramping after and during intercourse from stimulation of the cervix. This can be especially true if you have not had intercourse in a while (for example after delivery of a baby). Give yourself time and take it slow especially if this is the first time having intercourse after delivery.

See doctor: I suggest you have a examination by your doctor to evaluate the reason for your pain. This can't be evaluated online