My chi/pug has in the last two weeks has started coughing, and today we were walking and when she coughed, saliva came out. What's going on?

Could be a number of things, she could have inhaled something irritating, could be a virus, could be kennel cough, could even be a heart murmur. There are a number of possibilities, but no one here can diagnose your pup.

Also dogs with short snouts such as yours are prone to respiratory or breathing problems, they are also subject to reverse sneezes, and other piggish sounds.

You need to seek advice from your vet to rule out any medical problems.