Can we get a flat belly just by running every day, without doing any crunches?

please see and ENT specialist and get a nasal endoscopy done to know why are you having recurrent cold and breathing problems.

High fiber low fat diet followed by detox diet is the best diet for weight loss.take plenty of water everyday. Take small and frequent meals at regular intervals. Avoid outside food completely. Ask me directly for customized diet plan for you. 

Don't skip meal in fact take small and frequent meals at regular intervals to lose fast.