3MO throwing up?

My daughter has been throwing up after every feed even when she hasn’t ate for a few hours, she still throws up & she’s spitting up more than normal.. She has no other signs of sickness, no temp I’ve been checking like crazy.. She acts fine, happy, giggles, smiles, babbles.. She’s having normal wet & poopy diapers.. The throwing up has been happening since yesterday at 5am.. i have been making sure to burp her & keep her upright for 20-30 minutes after each feeding, but it’s not helping.. She throws up almost immediately after eating.. I do breastfeed her, I haven’t eaten anything out of the normal, & I haven’t had any dairy. I’m not sure if she just has an upset belly & it’ll pass in a little bit, acid reflux is acting up or something else is going on.. She does have a doctors appointment later today, but I want to see what you guys think..