Often when I'm usually stressed or thinking about something way too much, I get this nauseating feeling in my stomach and I feel lightheaded. It's almost like pressure and it feels like it rushes through my whole body but mostly in my stomach. I start getting warm and my heart is also beating rapidly. It's not the first time but it's an awful feeling. Anyone knows what this could be or how to get rid of it? I can't think straight while feeling like this, it makes me feel so much worse about the things that stress me.