I would make an appt to see Ob Doctor. There could be many reasons for missed period Hormones, Weight loss or Weight Gain medications Stress Anxiety. And The pains Could also be many reasons Gas Stomach Flu Ovarian Cyst . Best way to find out is Doctor. Because we could guess but honestly without test being done only could speculate.
Make an appt. it will ease your anxiety and also get down to trhe problem. Good Luck :))))
My advise to you go get a blood test done