Thanks for your query.
I am surprised that you are making a 7 month baby swim which is not advisable.
You mentioned that the baby shivered while having food and this happened the third time. It has to be seen whether it was shivering or convulsions. A better description of the movements would help us in coming to a conclusion.
I suggest you see your pediatrician
and seek his advice.
Wishing your baby all the best.