Weird period or pregnancy? I need advice please!

So this has been a really weird 3 weeks for me. First of all, I am almost always on time with my period and very regular. My period starts out as spotting for two days, then a usual flow for 1 or two days then spotting for the rest. I only get cramping and cravings during my period. Also the week before my period I pms but nothing unusual. So my pms started 2 1/2 weeks before my period was suppose to start it was very strange. I was craving every type of food imaginable. Also I never have lower back pain and I was getting that along with headaches on and off for about a week. My period started two days before it was due. It was a different and weird period though. I didn't spot at all I started really heavy and the cramping was unbearable and I was extremely nauseous. Anyways the next morning I woke up and my period was completely gone. It's been 3 days and I just had the smallest amount of spotting today and it then there was nothing. My body has been really off the past 3 weeks and I was curious to why this would happen. Especially if I am usually very regular. This month we didn't try that hard at all due to our busy schedules. Anything is possible and I've heard of implantation bleeding but didn't think it could be that because it was so heavy on the first day. I would love to hear some comments or opinions on this! Thank you!