Adding sugar to 10 month old baby home made food..?

I have never been doing so, until 2 weeks back when he fell sick with diarrhea (owing to the anti biotic he has been taking for fever) and vomitting...(owing to a bad cough)...I have since been giving him arrowroot porridge so as to alleviate the diarrhea...I have been adding small quantities of sugar since the porridge is absolutely tasteless.... prior to tht I have been sweetening his food using fruits like banan/apple... but currently not doing so since he completely throws up when I offer those fruits... Is it ok to add sugar at this stage? It would be temporary until I start adding fruits to his food to make it sweet... he does not eat unsweetened/bland foods...:-(