Regurgitation

Hi mommies, ftm here and require some help. Baby has a few regurgitation after feeding but most of the time it is whitish (similar to milk) in colour. However, the regurgitation was bright yellow this time round and when I googled for it, the information got me concerned. Would like to ask mommies if any of you have seen such regurgitation before. Baby is on mixed feeding - formula and breast milk with formula being predominant source. #pleasehelp #1stimemom