My baby was also born in May. He hasn't had your baby's symptom (leg's shivering). I remember there was once that I got medicines from my doctor (cos I was sick) and he told me that the medicines were fine to baby even though I breastfeed my baby. However, after feeding my baby, he had a very serious swollen eyes. Fortunately, the swollen eyes were gone when I stopped breastfeed him for 4 days. I have told my doctor about it and he said the medicines were fine to most of the babies, but my baby might be in exception as he probably was allergic to some kind of medicines.
Is it possible that your baby is allergic to the medicines you had taken during the pregancy period? I think you'd better see another doctor to double check your baby.