Most common causes of pelvic pain at this age could be pelvic inflammatory desease , ureteric stones ,appendicitis
or urinary tract
since you don't have any other symptoms wait for the periods.After 10 days of negative test and missing periods ultrasound scan may be repeated to know the cause for Sharp pelvic pain.
If everything goes normal I suggest you to take progesterone
to induce periods and if pain continues to start on oral antimicrobials for 7to 10 days.If you are feeling better after 5 days of antimicrobials your husband may also have to be treated with antibiotics for 3 weeks or ask him to consult an urologist
to rule out prostatitis or any other genital infection
.Till then condom may be used.
Hope my answer helps you.