Dog Training Supply

My dog is a chihuahua mix and is acting wierd. When my mom calls to her she wags her tail and pees becuase she was so excited. The past few days, she hasn’t been herself. Just now my mom called her and my dog didnt wag her tail or run up to her. She just put her head down and crawled up into a ball. She sometimes randomly shakes like she’s having a miniture seizure and sometimes she vomits but she’s done the vomiting since she was born. She just seems so down and depressed and when you hold her, her body is really warm and she’s not an outside dog. Another strange thing is that she opens her mouth up every couple of minutes and her gums look really red. My dog NEVER goes around other dogs or we never take her for walks cause she hates leashes. So she couldn’t have possibly gotten anything from another dog and we got her rabies shot almost a year ago. Do you think my dog is sick? Thanks!