I'm crampy today, to the point that it's uncomfortable, and I'm trying not to freak out

Has anyone else experienced cramps at 17/18 weeks? Should I call my doctor?
I'm telling myself that it's because I'm pretty constipated today and/or I'm growing. They feel just like menstrual cramps.. and I have no bleeding or spotting.
Re: Cramps?
diagnosed with unexplained infertility, regular cycles
Baby #1: ttc naturally for 3 years, 6 yr old daughter
Baby #2: ttc naturally for 2 years, 2 yr old son
Baby #3: ttc naturally since August 2016
I don't think you have a problem with no spotting or bleeding but if it makes you feel better then I would call your Doc. That professional reassurance can help a lot.
I am thinking/hoping it has to do with growth because I just recently started feeling baby move like crazy so I'm thinking he/she is just getting bigger. Plus I'm not really showing that much and I know that will change soon!
BFP#2 7/28/13 EDD 4/9/14 Birthday : 4/10/14 Adalyn Nanette