EMERGENCY - Airline Refuses to Keep Medication in Fridge on Long Flight

Hi guys.. I'm in a dilemma. I'm going on a long flight with a medication that needs to be frozen or very cold. The flight is 15 hours long. My airline wont let me store it on their airplane's fridge. I have questions:

1. What can I do to make sure its as cold as possible for as long as possible?

2. Does tsa allow dry ice in a carry-on?

3. Are there portable refrigerated coolers I can store it in? Can you suggest some good coolers?