Braxton hicks?

I'm 26 weeks today.  I'm trying to determine if I'm having Braxton hicks contractions or not. Some days I feel more uncomfortable especially today I just feel my stomach tighten as if the baby is stretching maybe? It's tight (no  pain) for about 30 seconds and then goes back to normal. I just feel huge and heavy when this happens. Like I mentioned today I just feel less energetic and uncomfortable. I'm resting for the most part.