Feel like I'm going crazy!

I've been a bit stressed at the moment and quite busy, and although was told by a doctor my lump on the back of my neck is nothing to worry about (apparently its just a tendon or something), I still worry I'll be diagnosed with lymphoma and am convinced I'm going to die. I just had a moment to myself to relax on the bus, closed my eyes and tried to do some breathing exercises, and out of nowhere I felt really light, almost like I was floating, and had this weird intrusive image of my body ascending to heaven or something like that?! I'm so worried this is a sign I'm about to die...although obviously it's more likely that weird intrusive thoughts and images happen based on our deepest worry, which for me is dying. The OCD side of me can't stop worrying that is a sign I'll die - has anyone else ever had these weird kind of feelings or scenarios play out in their mind?!

I even felt like as I was passing by things like trees my mind was just saying goodbye to everything and seeing how I would react. I almost feel like it's my OCD daring me to think these thoughts and I just need to laugh it off and move on...it's just so easy to be sucked into constant doubt from these kind of thoughts that they are right and I'm actually going to die soon

Feeling like you are floating is a very common anxiety symptom and if it were a true precursor of death I would have died years ago. The problem with anxiety is that it creates fanciful illustrations based on what you are feeling but are actually just a creation of your mind in it's current state. Because of my symptoms my existential thoughts have become so extreme and strange and have been with me 24/7 for months now. All because I had 2 weeks of DPDR early this year, but the floating thing didn't effect me like that. I hope it passes for you but you can find yourself easily stuck in an intrusive thought loop which can make life a misery

You copied my name

Everyone dies, my friend, and everyone has to find a way of coming to terms with that inescapable event.
The sensations you report are clear symptoms of anxiety and will settle as the anxiety does.
That's what you have to hold onto while your surf the wave until it breaks and ends.
Anxiety is very unpleasant and sometimes very frightening.
I've had three protracted episodes of derealisation and extreme anxiety.
Time, eventually, restores my emotional and psychological balance.
All I can suggest to you is that you're worried about going crazy, you're not going crazy, because crazy people usually don't know they're crazy until they've been diagnosed as such and are also usually not suffering symptoms.
Your symptoms are not dangerous and will do you no lasting harm.
Be gentle and kind with yourself, rest and eat well and try to focus your attention externally, instead of on your symptoms.
It may take some time before you feel well again, but you will. Find a good anxiety therapist and talk over your fears with him/her. Better out than in!