4 months baby (phlegm and diarrhea) protein sensitive

Hi, my baby 4 months old. I worries she have Protein sensitive.
Fully formula, between the 4 months she change 5 brand of formula. Worries will have any side effect to her.

1. Annum Day 1-10 (constipation)
2. Nestle Nan Pro until 3 months old (Baby sitter said the milk not suitable her, because of her poo poo like diarrhea) for me, I feel like a lot of phlegm
3. Isomil only drink 1 week, 3 months ++. I feel she almost constipation.
4. Nestle Nan H.A. only 1 week, 3 months ++ (suggested by doctor, he said : after drink this no more phlegm mean she allergic, if yes then is environment caused) I feel she have phlegm too, poo poo and gas super smelly. And I feel her when poo poo and gas like not well.
5. Aptamil, drink 1 week ++. (After 1 week her poo poo like diarrhea. 1 day almost up to 4 times). So baby sitter said let her drink isomil to stop her diarrhea first.
   Now drinking isomil.
   But this few days I feel her phlegm a lot and hard to Breathe)
   Now I have no idea, dunno what to do. Baby sitter said let her drink isomil to stop diarrhea then drink aptamil again to test. She said when poo poo not nice is mean the milk not suitable her. So must change until the poo poo is nice mean ok.
   For my view I worries change many type of brand of milk and she is too small will have side effect.

And now I planning change to aptamil PHP.

Kindly advise me, thank you.