relieve constipation???

Hannah
Mommies I need help! I got very sick Tuesday morning and was in the hospital all day with an infection and severe dehydration unfortunately my supply has been low and I’m planning to make an appointment with a lactationist to see what we can do, but because of this the big stash I had in the fridge has decreased significantly and on Tuesday and half of Wednesday my daughter had to drink formula (similac pro-advance) all day instead of breast milk 😩😩😩 she has not pooped since tuesday night, she farts stinky farts lol but every time I see her try to push she cries like she’s in pain..... I believe she’s constipated because of the formula 😭😭 usually I wouldn’t worry if she was just on breastmilk because that seems to happen every now and then but I’m starting to get a little concerned. any ideas or products you moms recommend to help with this???? She’ll be 2 months on the 5th. Please let me know !!