Dairy free milk alternatives

So my daughter can not digest milk anymore it seems like. She has been constipated and upset for weeks and weeks. We finally cut milk out completely and she pooped twice in one day!

So I’m looking for an alternative to whole cows milk. Her doctor said she needs to continue on whole milk because she needs to gain a little more weight I guess.

I bought this soy milk and hoping this is ok. She only has about 16 oz a day so two cups. This was the only thing I could find with omega 3s, protein, vitamins and no sugar added.

If your kid is dairy free what do they drink instead of cows milk?