Its there any relationship between shellfish alergie and symptoms like dizyness stomachache? I feel like if a had a drink

Possibly. A significant shellfish reaction (or any severe food allergy, for that matter), can result in a loss of blood pressure that can cause dizziness and stomachache. However, people with this severe a reaction are very, very sick, and often need to call 911 to get transported to the er. You should discuss your situation with an allergist to figure out what's going on.