Econorm sachets contain probiotics, and yes can be given in a 7 month old child with loose stools. You can give half a sachet twice a week. I usually prescribe enterogermina as a probiotic. Probiotics are the first line of treatment.If the symptoms persists/ worsens we may have to introduce an antibiotic.
Next Steps
You should consult a paediarician and try and find out the cause of the issue. Also the doctor will be able to check the hydration status of the child.
Health Tips
Keep a watchful eye on the urine output, as decrease in the urine output would suggest dehydration. Maintain good overall hygiene as kids of this age usually put things in their mouth which can introduce infection into the body that may cause loose stools.