What Causes Delayed Periods With Severe Abdomen Cramps And Spotting?

I m 20 and had unprotected sex on 01/04 but didn t get my period on 01/20. On 01/15 I got really bad cramps and on the 19th I had brownish pink spotting. But I have had cramps every day with no period. Pregnancy test are negative and I feel dizzy when sitting up or looking down. No painful urination, I haven t had nausea or vomiting. Sometimes I get sharp pains on lower right side of my abdomen, sometimes its the left side only. I ve had a little bit of white discharge but I don t feel pregnant. Please help.