Cramps at end of period

I had a period that lasted like a week. I tend to have long periods sometimes as my flow is not at all heavy. This month was great in that i had no cramps at all before or during my period. I tend to have something. I did have a bit of bloating and a lil tenderness in my breasts. My drip days spread out long this month it has been about 8 days and tho my drip is practically non existent today, i started having cramps. First was on my right side but now it kinda moves to my womb a lot and seems to shift to the left side as well. I have had similar feelings before in that at the end of my period i get some cramps that feel as if my womb is trying to squeeze every last drip of blood out. I sometimes feel this and a shaking-off sensation during my period. i used to have irregular periods when i was younger but they have since sorted out themselves and i am quite regular now. I want to know if this is normal or if something may be wrong. Should i be concerned. I think I have some gas as well, can it be the gas making it seem worse?