cramping pains!!!

I'm having these cramping feelings on my belly, my stomach will get hard thenease off!!! My bf was worried so he massaged me last night but it didn't help! I am Constipated though, I'm not having Braxton hicks but my stomach does get tight! I'm 18 weeks and 2 days...I'm a little worried because I been reading about the other moms having their beautiful babies really early! I don't know maybe I'm overreacting, but it makes my toes curl every so often.. hopefully it's just constipation!! 😬