Thanks for the query.
Though previously there was no stds, in pregnancy
reactivation of some infections can occur or new infections can acquired by skin to skin contact also. Decreased immunity during pregnancy will add to this.
According to your description there is possibility of infections like herpes
, yeast infections
As vaginal infections can sometime lead to premature uterine contractions, better to consult gynecologist once and get examined to find out the possible cause and take treatment accordingly.