Feeling crampy?

I'm 16 weeks today and every now and again I feel I think crampy.. it's kind of like period pains but comes and goes.. I had trouble sleeping last night and every time I turned and tried to stretch I would get a sharp pain on the side I turned and stretch. Is the dull cramp feel I get normal. Is it round ligament or ? Can anyone else relate. We saw baby last week and all was well then :)