While fasting can I take steam for cold and chest congestion?

If the steam goes directly to your lungs, then it won’t invalidate your fast. But if the steam goes down your esophagus and you swallow it and it has moisture, then it would break your fast. If you have to take this steam due to your situation then you may do so, since you have a medical excuse, and then make up the fast later when you are able to.