Baby lifting legs during the night

My baby is 16 weeks old and when I put her to sleep at night she starts to lift her legs up, she is uncomfortable and starts to fart and eventually wakes up. She is tired, I am tired - only thing that helps is when I breastfeed her while laying down and she falls asleep in that position but I cannot rest properly this way. What is going on? She doesn’t have colic, we use some kind of drops for gas and I even try to put her on a narrow pillow. Nothing helps!! This is the only reason why she wakes up, and it is 5-6 times a night. I think she would sleep all night long if this wasnt a problem.
Anyone else has this kind of situation? Thanks.