I had the same pain on the left at 5 w, then 6w on the right side.
I went to see my gynae to have a peace of mind, upon ultrasound i get to see the ges sac . she ruled out ectopic pregnancy and told me its growing uterus that causes the discomfort.
it's quite common, unless the pain is very unbearable then its something else. go see your doctor if you're anxious about it.