Thanks for your query.
Complementary feeding should be started after 6 months of age.
Initially start with boiled rice water,boiled pulses water,coconut water .
One thing to be introduced at a time in small quantities.
semisolids are to be introduced later.
Since now she is passing loose stools,give oral rehydration solution sip by sip after each loose stool,
like lactobaccilus for 2 to 3 days.
Wishing your baby good health.