My pedi suggested juice/water or pedialite for my 2 month old

Marli • Lottie Mae norm 3-23-20. Liam Thomas🌈 born 4-7-17. Angel baby 5-4-16. Hubby & I married 11-1-14. Have two Pomeranian `babies`.
So we went for his 2 month checkup today. Because we've had constipation issues I matter which formula we were on (we both formula and breast feed)...he gets constipated and strains and passes hard solid poops (about the size of a Chick-fil-A chicken nugget)
So between that and living in a very hot/humid climate he said that when babies are too hot or too thirsty they take water from their bowels to power them. 
So he suggested we give 2 4 oz bottles of pedialite or baby safe juice and water mixture per day. That seems like A LOT to me. And after researching it...seems like most people doing give juice until after solids at 6 months. 
Anyone had a pedi recommend this?
Would you do it? 
If so would you give the recommended amount or just an ounce or two a day?
People on Ovia were all screaming "your pedi is insane! Get a new one!" But he's been really great with everything thus far. I'm just a little concerned about this particular suggestion and would like input from other moms as to whether or not you've been told the same or something similar...

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