Baby constipation

Any quick solutions for fast relief for my 6 month old who is constipated?

Already tried prunes and mommy’s bliss constipation ease. Nothing works. Tried giving her juice and she refuses it.

Switching formulas is not an option because she’s allergic to cow milk and can only have the soy one... I don’t know what else to do, she’s super fussy today and refusing sleep and I think that’s why.