anyone else?

I am 16 weeks 1 day today, and for the past few days I've been really uncomfortable. My lower abdomen is really hard and tight and I feel like I have to pee constantly. I was wondering what this tightness is and if / when it might subside. 
Could anyone give me any insight? This is my first baby so please no negativity. I'm sure everything is fine, this is just all very new to me! I'm learning a lot about my body and pregnancy through this process. Thank you.