Should I switch or wait?

My daughter has been formula fed since birth. I’ve started to notice that she’s fussy as all hell (most nights it takes hours to put her to sleep & she will only sleep 10-15 minutes) she can’t really poop & when she does she screams like it’s hard & sometimes she will spit up. She has an appointment w/ her pediatrician tomorrow but not until 4pm. I tried to call this morning to see if I could get in today or just something earlier & nothing. I don’t want her to have to go through this another night 😭 A number of people have told me similac sensitive helps their kids w/ the same stuff. I’m just unsure if I should make the transition or get her doctors opinion?