Vomiting when my 3yr old ASD has a cold

I wondered if anyone can help, my little boy is 3 and from birth always struggled with food, 

everytime he has a cold he will eat food or drink juice and will cough and then be sick this can happen up to three times a day sometimes, summer months are so much better as he is really sick but as soon as the winter months come and he gets the slightest cold he’s constantly sick even with juice. I have him booked In at the doctors today but was just wondering if anyone else experienced this with their child and if there was anything you did that helped to keep food down.