Suffering From Headaches, Back Pain, Pelvic Cramps, Loss Of Appetite, Weight Loss. Very Light Bleeding. Is It Die To Pregnancy Or Ovarian Cyst?

Im 21 years old. For the last few months me and my boyfriend have been having unprotected sex (pull out method). Last month my period was 5 days late. I took a pregnancy test and it came out negative. It eventually came but was still very light and only lasted 4 days which is unusally for me. This month i have had headaches (which is uncommon), back pains, severe pelvic cramps , sharp pelvic pains, lost of appetite , and even weight lost. My period is here but it is still kind of light. I finally went to the hospital where they ran another pregnancy test and it came out negative. they said that it is possibly a ovarian cyst . should i ask for a pregnancy blood test or maybe even an ultrasound or am i just stressing over nothing. If someone could please help me i would greatly appreciate it .