I was diagnosed with a viral syndrome. Laying down I feel fine. Standing up my heart rate jumps up to 130-140, dry mouth, extremely weak, headaches. POTS?
It sounds like you may be dehydrated, so would start drinking water and continue to drink more fluids. Often when you have a viral illness you don’t eat very much and have increased loss of fluids from fevers or vomiting or diarrhea. So start drinking healthy fluids!