frustrated

my daughter will be 6 weeks on Saturday. up until this week she has been nursing like a champ. she is currently taking zantac for reflux which is helping, and gas drops.

this week at the bedtime feed, she has started to get really frustrated. she will latch and then pull off and cry. she will also pull her head away, and stretch out her legs while crying. she gets very stiff. I have been giving her lots of breaks and burps to calm down, but its always the same thing when I put her back on. has this happened to anyone? all I can do is be patient with her and try and soothe her but I want to figure this out. any ideas?