Pre-term Labor?

I am a ftm and 34w1d. Yesterday I was on my feet pretty much all day walking around, when I was driving home I had a couple cramps that were pretty painful but they went away. Today I've been feeling nauseous on and off but havent thrown up, and have also had diarrhea, but havent ate anything that would upset my stomach. I have period like cramps that arent consistent, and recently I've been feeling like her head is pushing down on my pelvis (it hurts when I stand up, walk, etc.) I just saw my doctor on Monday because I thought I lost part of my mucus plug, but she didnt say anything or seem concerned. I don't know if this is all just normal or if I should call my doctor?