I know what you're going through. I also cause people to have reactions, like coughing and sneezing. On 2 different occasions I've caused people to gag, it was so embarrassing.
You may want to start by changing your diet. Eat lots of fruits and vegetables. Stay away from processed foods. Drink lots of water. I've tried several supplements but I have'nt really found any that work well. So, my advice is to save your money.