Exclusion diet

I suspect a mild CMPA for my LO and want to try excluding cows milk from my diet (she’s breastfed) to see if her eczema clears up. Thing is I’m already veggie and so will be going almost vegan with this diet. Should I take supplements other than calcium and vitamin-D? I’m already battling with mum burnout and am overwhelmed by the task of planning new meals for the next 2 weeks+, especially making sure I’m getting all the nutrients I need to EBF my hungry 5 month old.