Bulldogs World

I have an English and French Bulldog so would appreciate if anyone has seen this behavior in their Bully. I know this website is more geared toward English Bulldogs but am hoping maybe this issue applies to French Bulldogs also. My French Bulldog Eva that is 6 years old started last week on Monday having issues were she will start to shake and make some loud snorting noises. When the shaking occurs her whole body will shake as if she is scared and then she will seem like she is having a hard time breathing through her nostrils and want to lay down or avoid contact. She is eating and drinking ok just not active and happy like she normally was before these episodes began last week. The episodes last a few minutes and then seem to go away a few times a day. I took her to see the vet which is very familiar with Bulldogs and he did a chest X-ray which showed no pneumonia, checked her back which showed no visible of pain or injury, her temperature was normal, all of her reflexes were normal, and as a precaution started her on clavamox/Theophylline but the issue still persists. I will begin giving her some Temaril P tablets tomorrow since my vet believes that it may be sinus issues or could be reverse sneezing. Has anyone had this type of issue in their Bully and if so please give me advice on what it may be because I am a nervous wreck!!