Are the symptoms of feeling cold and chills (shivering) accompanied by any fever? If yes, then it can be a bacterial or viral infection.
If there is no fever associated then it can be due to hypothyroidism, anxiety and panic attacks, hypoglycemic attacks, hyperhydrosis(excessive sweating) and premenopause in women. Sometimes, patients who have recovered from a febrile illness continue to experience chills in the convalescence period.
It is advisable to first have the investigations for fever like ESR, complete blood count, blood culture, blood test for malarial parasite, widal test, x-ray chest or sonography to exclude any of the pathologies associated with fever. If negative, then other causes of chills should be looked for.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
It could be caused from an ovarian cyst(s) that have ruptured. If the pain and chills continue, or if she develops a fever she needs to be evaluated by a gynecologist for ultrasound. Ovarian cysts are usually benign growths and are not as uncommon as some people think. The only thing that causes ovarian cysts to become an emergency if they are large, if it is causing the ovary to twist, or if an infection develops. However, I believe that the cause of your wife's discomfort if from a rupturing ovarian cyst.
I hope she gets to feeling better soon.