Can allergies cause you to feel dizzy , have an upset stomach , headache and overall feel aweful?

Insufficient data: Please repeat your post but this time specify what kind of allergies you mean: Drug allergies, food allergies, or environmental allergies. If environmental, try to specify: House dust? Mold? Pollen? Other? Also bear in mind that a lot of what are popularly called "allergies", really aren't true allergies. Have you seen an allergist and been tested?