Help..nutramigen advice

Hi ladies,

Doctors recently swapped my 8 week old on to nutramigen due to her having a rash and belly aches. Before the swap she was on 4oz of aptamil every 3-4 hours. The doctors said she should be having 2oz of nutramigen every 3 hours but she’s starving, cries once she’s drained the bottle in 0.3 seconds and is crying for more after an hour. Can I just up it or would there be a reason why they said I could only feed her so little? Seems so mean to be starving her…

Thank you