My girl like to unlatch herself when she finds the milk flow too slow for her. So I also force her to latch on.
Also btw, it is is okay to breastfeed if you are sick, as the breastmilk contains a lot of anti-bodies that will help your son to fight against the cough. You can wear a mask while BFing if you are afraid. I was down with flu but I still BF my girl and her bed is next to mine but she was fine. =)