help me figure out this constipation?

N.
Baby has had what we lovingly call glue poo for days on end now. I initially thought it may have been a reaction to avocado and a mash containing white potato which has clogged her up a bit before but I cut that out at the start of the week and have been giving her a mash of sweet potato, carrot and apple thinking that all those foods should be helping her eh, move things along. She has had watermelon and pear sauce, sucked on chunks of broccoli... all stuff that is supposed to help. The only other thing she gets is baby oatmeal and breastmilk. 
This morning she is still doing her gluey poos. 
Any thoughts? Could this be a teething quirk? Teething ramped up for us this week with lots of drooling and discomfort. Other than that I really can't think of anything