I didn’t make up the missed fast days of Ramadan in past years due to constant migraines and stomach pains. Should I pay the kaffara in cash value to feed poor people?

It is permissible for you to pay the cash value of the meals to the poor and needy. You should know that the Kaffara is for delaying making up missed fasting without an excuse. However, whoever is excused, like in your case, you must make up missed fast days only.