Pleghm in babys throat

Hey ladies ! Just wondering if any of y'all experienced this with your babies but I gave birth to beautiful baby girl Jan 27 ! EDD was Feb 11 but she was ready to come on out lol anyway here the last few days my husband and I have noticed what sounds like phlegm/mucus in her throat. sounds like she needs to cough/clear her throat but can't 😩 ive also woken up in the middle of the night to her choking/gagging in her sleep ! 😣😣 very scary as a FTM ! She has her 1 month check up March 1 but we are very tempted to see if we can get her in sooner. She also has puked a lil breast milk back up during these choking/gagging episodes so I was thinking it could be acid reflux...?? idk if yall have gone thru this with ur newborn y'all help me please ! Thanks !