10 month olds formula! Help!

J

Okay so I usually buy my sons formula from Walmart. It’s the parents choice soy formula and for some reason it’s completely out of stock in store and online?! He started out using alimentum when he was first born due to a rash he got from regular formula so they thought he had a milk allergy. So then we switched him to soy around 5-6 months and he’s not had any problems with it at all.

My question is what formula do i buy him if they don’t have any of his regular soy formula?! Should I try just a regular non soy formula just to see if he can tolerate it since he’s older now?? Should i buy the more expensive name brand soy formula?

I have to go to Walmart within a few hours to buy some and I’m hoping they have it but if not what would you recommend us trying??