My period was supposed to start on sunday but came monday as a light spotting, today is tuesday and im experiencing cramps with little light spotting also. should i be concerned ?

Women's cycles can vary depending on many things including: hormonal fluctuations due to stress, too much exercise, weight loss/gain, thyroid imbalance, etc. Most probably, this bleeding will self adjust so that your cycle is regular. If you are concerned about other causes, or you have other symptoms, talk to your Dr for testing if this pattern persists.

Yes, especially if you had unprotected sex. A home pregnancy test would be advised. Good Luck