Sharp Pains!

I'm 18 weeks with twins & have today started getting this really sharp pain to my lower right hand side stomach. It's really uncomfortable to walk, as is getting into a laying position and then likewise for getting back up.

Has anyone else had this? I know you can get sharp pains due to your uterus expanding but I thought they would be more like the odd shooting pain.

This came on early this morning and is really uncomfortable. Should I be worried? Xo