Why does my Bull Terrier puke when nervous or over excited? Walking to the park or New places with other dogs?

She is 2-3 yrs. old. Never really drowls or slobbers until over excited. It is a real thick hy foamy looking vomit. Clear with thetexure of the white hiness of a cofee, It is thick. Like she swallows her spit allday and then throws up when in anxious situations. I also noticed an over excessive licking disorder, she lays on tummy and scarfs on her paws daily when left alone in bed or on floor when no one is paying attention to her She also will salivate alot during licking of paws, leaves huge drool spot often. And the dang dog chases it's tail when over anxious or excited, sometimes when shes left alone. It's really weird seeing a dog do all this, all disorders could happen daily if in specific ways. I have medication, but dont like the drugs or the idea, and we do not try and promote any of these behaviors. I will loudly say no and try and make her sit and re-focus on me. It is a difficult task and i havent seen that much change. Just a funny dog. What do Ido