Racehorse knows her stuff. Agreed, we need to know what nicotine strength and what flavors you are using.
It is quite common for new vapors to cough when they begin vaping. Warm vapor is different from warm smoke from cigarettes. It took your body time to adjust to smoking, it will take some time to adjust to vaping, too.
Understand that it is not necessary to lung inhale the vapor to absorb your nicotine. The nicotine that is in water vapor is a different size molecule and is absorbed in the mucus membranes of the mouth and nose. So for beginners, it is suggested to do a "mouth inhale", hold it there for a few seconds, and then exhale through both the nose and mouth. As you adjust to the vapor, you can gradually learn to inhale into your lungs like you did when you smoked.
Drink plenty of water. The Pg and Vg in vapor pulls water from our tissues and can cause dehydration and dry mouth/throat, so this must be replaced.