Quite possibly gas. Early in pregnancy your stomach bloats and flatulence is present in over 90% of pregnancies. If it's not that, keep in mind there is a heap of change occurring down under, and some women are more likely to feel those changes than others. I don't reckon it's cause for concern, but if your mummy instincts are kicking in that anything is wrong, it's best to follow those instincts.
Twinges are most likely everything expanding inside and down there and since your 6 weeks might still be apart of the whole plantation process ....but if you have a bad feeling always good to ask a DR.
A lot of weird feeling you shall feel...lol its only the beginning... Hope that help alil