Welcome to HCM.
Gastro can be caused by bacteria or viruses . The problem with being nauseous all the time is that you can struggle to rehydrate orally . For that reason it is often better to receive intra-venous therapy. Not only fluids are needed but also electrolytes and probiotics or antibiotics. Please consult your doctor because electrolyte imbalance
has the potential to be life threatening.
I trust you get well soon.