Is this anxiety or something serious

Abit about myself just incase those who don't know me. I have been suffering with anxiety for over 30 + years I am 41 now. The newest symptom i have been getting from 3 years ago which it stopped and returned full force the last couple of months. I can hear my heart beating in my ear and head it is very clear and sounds like my heart beat. When this happens my ear plug up and i feel horrible head pressure that i cannot not move. I feel like I'm going to loose consciousness. its a very scary feeling. Like I'm stuck in my body and cant come out of it until i calm down. I have been taking clonazepam half of it when it happens and after 10 mins i start to feel a bit normal again. I am terrified that I have a brain tumor or brain cancer or anyerisum happening. Literally all those symptoms start happening at once. I literally try to find my purse take half a clonazepam and call someone to talk to and pace back in forth in my hallway until I feel a bit normal. 3 years ago I did go for test I had a CT Scan, MRI and MRA on my brain because of the Heart beating in my ear and got headaches from it. I saw 2 ENT, and Neurologist all normal. But for the life of me i cannot remember if it made me feel the way I do like I'm going to pass out and lose consciousness and blocked like I couldn't walk straight or sit because of pressure. Please if anyone has experienced this please respond. I don't know what to do. I am terrified.

I am experiencing anxiety for almost a year now and the physical symptoms that I’ve had so far are: all body numbness,nausea,headaches,racing heart,stomach aches,cold hands and feet,insomnia,tired eyes etc. I’ve read on other anxiety forums that anxiety might cause a lot of physical symptoms even if you dont have any underlying diseases.If you have done all tests and have consulted with your doctors and they’ve said you’re fine then it might be anxiety.As for the beating heart and feeling it in your ears that happens to me too,accompanied by my heart racing.In my opinion take the clonazepam only If the physical symptoms are unbearable.I was recommended to take half of a xanax(alprazolam) only when I was in very very bad conditions(when having a panic attack for example).
what I do to avoid those situations is I dont give in to my thoughts.
A week ago I had this intense fear of dying in my sleep and spend a whole night just worrying.
So the thing I advise you to do is try so muscle relaxation techniques or breathing exercises and try to not react or chase bad thoughts.
Hope this helps🤗