A brain tumor can be diagnosed by proper examination with your Doctor, if you think you have it, talk to your doctor, ask for a full examination so it can be proof that it is there and can be treated as soon as possible if you DO HAVE that..so do it, asap...
BUT..if the examination proof that there is nothing wrong with you physically, it means you do have symptoms of anxiety. When you have this anxiety, you would feel those physical symptoms you mentioned above and sometime you even have what it's called as "Psychosomatic" when the body really shows and/ feels those sickness and problems while there is NO PROBLEM physically happen actually.
How to handle this anxiety?
Fight back ;)
see your psychologist, find what's the core of your problem that start the anxiety, perhaps the fact you lose your job, or could be other things you just gotta find it out with complete psychology tests and/ interview.
After you know the core of your problem, you can work it out.
If you don't think you can do this alone, find some friends you can hang out with and talk about it. If it is possible join a group that is provide for anxiety disorder people - usually your psychologist would know where to find it in your town/area.
As long as you can handle it, pls do not use any drug bcs it is not solving your problem often just easier but failed to train you to be a fighter..:)
you are a great young man, don't be afraid now..FIGHT BACK ...
The best thing for fighting anxiety this far, without drug, is involve in sport you like. Set the highest aim you can imagine, like follow a championship or tournament. If your core of problem is anger and disappointment (you have to know this from your psychologist later), try to join sports that require lots of hitting, or power like tennis, badminton, martial art, weight lifting..etc..
Doing a competition is not for winning it really, it's for your training to control yourself mentally and physically, focusing your object and it's not a myth...it is reducing your stress and anxiety..
good luck for you, if they can do it, you CAN do it too ;)
It does sound like anxiety to me. And, it does sound like you have had panic attacks. Have you had any testing done to make sure everything else is alright? I think any good Dr should do blood work at the very least to make sure there's not a physical cause for your anxiety. If everything checks out okay you may want to think about therapy to help with your anxiety. Your Dr may want to prescribe meds to help when you have a panic attack. I know how awful anxiety is. It's your body reacting to stress. We're here to listen and help anyway we can.