why do I feel chill in my upper center abdomen ?

I'm not sure what you mean by a "chill."  If it's a more of a pain you probably ought to see a physician.

If it's not a pain - and since you have this only after dinner - my best guess is that it is related to what you are eating - or when you are eating.  Maybe keeping a food diary of what you eat and drink -  and when - and notie the time for onset of the "chill.'  This might help you figure out what foods, drinks or timing might be causing it.

Hope this helps.

Lynn