Well, you should of course scream from your diaghpram as much as possible to avoid damage to your throat or vocal chords or what have you. But since you say you are doing this its quite possible that any discomofort is just from the fact that your body isn't used to it. I reccomend drinking lots of tea. You want warm liquids to sooth the throat and avoid cold water and things like that. When I did screaming in a band I always had a honey bear with me on stage and I would just pour honey down my throat between songs, it helped A LOT. Even when you scream right its not exactly good for you.
I would say drink some warm tea for a day, but if it lasts longer I would say your technique is wrong, if it goes away then its probably okay. Just take it slow as your getting into it do it a little one day and more the next but don't go screaming for hours right out of the gates. Hoped that helped.