issues with baby brezza

Has anyone had issues with the baby brezza?  my little girl started showing symptoms of reflux a few weeks ago (around 4 weeks old) and was prescribed Zantac.  A few days later she had blood in her stool so we switched formula and I stopped using the baby brezza cause I had to clean it.  Yesterday (2 weeks from starting the Zantac) I finally cleaned and reloaded the baby brezza and started using it again.  After only a couple bottles she was back to the same reflux symptoms as before.  The more I think of it though she started the symptoms right when we started using the baby brezza in the beginning and stopped when I went back to hand mixing the bottles.  I'm just curious if anyone else has had an issue like this?  I'm starting to wonder if she even truly has reflux at all or if it's the machine...