Pain in abdomen..hard to describe?

I am 18 weeks pregnant and all day today i have had weird lil pains in my abdomen. they are hard to describe so ill list everything i can think of...for instance the pain spots span about the size of a dollar coin, they last 10 seconds. they dont feel like stretching pains...they alsmost feel like that feeling when you stub your toe or if you push on our belly on and get that weird almost painful like sensation in your stomach. I am not doing anything like walking around or doing anything strenious to cause it either. i dont know if this is the baby moving since i dont know what erflies or twinges feel like in my stomach, if someone could explain that too it would be awesome. Ive also been told it could be round lagament pain but i dont know what that feels like either...sigh