Loud sneezing or making sounds while eating makes me go mad. What to do in such situations without making anyone feel embarrassed?

There are people like you who cannot stand certain noises. I have a few cringing noises myself actually. If it is a person with whom you eat most meals, you might be close enough with that person to ask whether they are aware of the noise they make. You would know if they have an impediment which makes them eat that way. Maybe on-one told them before. If it is a total stranger, don't talk and instead, see if ou can remove yourself from the area. If you can say anything, you can also tell them that the noise they make sounds sloppy and apologize. What you have is called "misophonia". Good luck!