Ask a Gynecologist and Get Answers to Your Ob-Gyn Questions ASAP
Statistically is would be quite rare for you to be pregnant, but nothing in medicine is impossible. Because you have a history of a tubal ligation it is advisable to see your doctor ASAP for a blood pregnancy test. If you were to be pregnant chances are it would be a tubal or abdominal pregnancy, both of which could represent serious health concerns for you.
Furthermore, if you are not pregnant, it sounds as though some testing may be necessary to account for you symptoms.
I would not expect any of those things you mention would mimic fetal movement. One possible exception to that would be if have a large fibroid coming of the right side of your uterus that, with your movement, produces displacement of internal organs that simulate perceived fetal movement - however, I would not expect any of those things to cause such a sensation at rest, such as lying down. Muscle spasms or fasciculations may produce such perceived movement.