Hi there new to the board so be gentle with me

I have a 9 week old Yorkie pup who has had the 'runs' for 2 days now. The breeder was feeding him on weetabix, so I gather the runs are due to me introducing him to wet food. Now my query is - I would like to feed him on a diet of chicken and rice plus a small amount of Iams dry food in the evenings. Is it possible (safe) to pre cook and freeze the rice and chicken for future use? If so how do I defrost it? Would I need to re-heat it before I fed him? Thanks in advance for any replies guys.