Late conception has to be ruled out by one blood test
for beta-hCG if she took 2 pregnancy tests in very early weeks.
Other possibilities are PMS, pelvic or urinary infection, endometriosis
etc. Here, I suggest to undergo one pelvic USG scan and urine test - routine & culture to pinpoint the diagnosis. Kindly, consult with her doctor for proper examination.
In the mean time, she must take balanced diet, drink plenty water, keep bowel habit regular, take some anti-spasmodic medication (drotaverine
) and apply muscle relaxant
gel on the back/ take hot compression. Good luck.