Since yesterday i've been feeling weak, very nauseous, kinda dizzy and feeling a fullness or pressure in my stomach (middle) can it be a virus?

Ileus: Though difficult to give specific advice, what you're describing may be what is called an "ileus, " often related to a viral gastrointestinal infection. Feelings of fullness and abdominal pressure with nausea are typical when the gut's natural digestive movements (motility) are temporarily altered until the virus clears. My general recs: 1) see your md if worse, 2) keep well hydrated.