Hi, i am a mother of 5 children, aging from 3 yrs to 17 yrs. There is a small possibility that the area he recieved the shots is still a little sore. On top of that he probably is teething, and it more than likely is not fun at all having the two coincide with each other. What ever you do though, do not stop breast feeding him!!!! I breast fed my youngest for 16 months,she does have some lactating issues, but is very healthy. Your breastmilk cannot be causing any feeding problems with him. Sometimes though, if you eat foods that tend to give you gas, he could get gas, and the same with spicey foods. If you are feeding him solids, you may want to stick to the traditional method of introducing one food at a time, and for a solid week each, i did have a child who had trouble digesting some of the foods at first. I hope this helps some, and by all means, if you feel you should change your pedi, do so, we all have that mothers intuition, and can feel when something is not right, or being treated correctly.
Good luck, and god bless,
R.