Breast milk

Can breast milk spoil? Since busy schedule at work, sometimes I do skip my meals & no proper healthy meal. I buy food outside which find it less hygienic & too much of msg. In this case, is BF still good, safe & nutritious? When I pump I see so many bubbles . after baby drink the frozen which been thawed she keeps crying due to tummy bloated... my baby is 3M 20Days and I’m still Controlling my food since she has trouble to adopt it.