So I’ve been dealing with anxiety and panic attacks for a few years now (22m) and I’ve been on beta blockers 2 years ago which helped  made the panic attacks more manageable.
I stopped taking them for probably a year now, except for the occasional panic attacks to calm my racing heart.
However lately my anxiety levels has been over the top, panic attacks almost everyday but nothing unusual I’ve been able to get through them. 
Except for the last 3 days when i started getting new symptoms that I’ve never experienced before. It’s this dropping sensation in my body idk how to explain it but it feels like something fell inside of me and i feel like fainting for a second, I’ve been getting them a few times a day which usually triggers a panic attack.
But the last 2 days whenever I walk i feel like falling i feel so lightheaded and i start making worst case scenarios its awful. It seems to go away when i lay down or sit down. But whenever i stand up i immediately feel like my body is so weak and light and like I’m about to pass at any given moment. Which makes me freak out and immediately start thinking I’m about to die. I’ve been trying not to rush to rush to the hospital as they will probably tell me everything is fine. But it’s really hard and my stress and anxiety are driving me insane. My body is always on alert mode as i keep thinking i could die at any given moment. I really don’t know what to do
Does anybody else experience this symtom?  

(Sorry if there’s any mistakes..English is it is not my mother tongue)