Symptoms of weight loss, heart palpitations, stomach pain, and respiratory distress. viral or anxiety?

Virus vs anxiety: Anxiety last a long time (weeks-months) and can cause a vicious cycle of damages, while a viral infection is self limited in time ( days to a week max) and people recuperates rapidly thereafter even without treatment. Lasting anxiety needs long lasting treatment with psychotherapy or medications or both.

Could be both/none: So many conditions can present with those symptoms. Your best bet will be to get a thorough evaluation to find out.