Cow milk allergy

My baby went to the doctor today because I found some blood in her stool. Doctor said if it because she is allergic to the milk protein in the formula. All I have been drinking is milk so I have to stop breastfeeding for two weeks and start a no milk diet so I can be able to breastfeed. Doctor gave her nutramigen and I started to feed her only that. Ever since she has drank it she has become more fussy, seems more constipated and doesn’t want to go to sleep. She wasn’t like this before🥺What do I do? Should I switch to the similac formula for cow milk allergy or is there another formula that I should give her? Any tips?