Can babies randomly develop sensitivities to formula??? How do you know if their formula is the problem ?

Pissed right now bc my mom watches my daughter on Wednesday night while im at school, my daughter is 8 weeks and a very good baby, only cries when shes hungry. After I left I guess she started screaming for hours and crying & my mom said she kept grunting/scrunching up like her stomach was hurting. So she gives her a baby lax (which is fine w me) but also goes as far as getting her a different type of formula without asking me or even calling me to let me know that something was wrong with my daughter. My daughter has been on Gerber Good Start Gentle since she was 3 days old and has pooped at least once a day every day on it & has been happy & having no problems, could I need to change her formula after 1 day of an upset stomach??