Hello ma'am, thank you for your question!
As you may have guessed, your baby must basically 'learn' to digest these new foods. This requires a period of adaptation
At this age, encourage your baby to drink often, a few sips at a time of milk, water or other fluids, as this is the best way to soften the stool.
Continue with exercises such as bending his knees towards his chest when he is on his back, or simulating a pedaling motion :)
If the situation persists, I recommend that you consult your pharmacist:
PEG-3350 Tasteless and Odorless Powder (Lax-A-Day, Restoralax and other brands) can be diluted in a small amount of liquid and given to your child to drink. The powder is given according to your baby's weight, your pharmacist can tell you exactly how much.
I hope this has been helpful to you and if you have any further questions, please do not hesitate to contact me
Tom Samaha, pharmacist