Suggest Treatment For Weakness In The Chest And Dizziness

Question : For last 3 years I have had numerous symptoms that no one can explain, but all tests has come back normal. It all started in march 2014, I use to had urine starting trouble (urine hesitency), it use to take very long time to start urine, this problem use to come only when i sit longer during office. So during that time i had consulted a urologist who did urine analysis, culture and ultrasound for kub region and testicles. Everything came normal. Doc prescribed some antibiotics and that didn't work either. So i stopped eating them after a month. After couple of months the problem gone on its own.
Then from mid july 2014 i started having weakness in my chest and also having breathlessness(not able to breath deep and easily). So i had consulted a pulmonologist who did pulmonary function test and said it is normal. But breathlessness and weakness in chest continued. I also use to had muscle twiching inside my chest. One day my breathing difficulty worsened and i got a panick attack soon after that. I was joined in a hospital and doctors did all the tests that they know (CBC, Thyroid, HbA1c, Lipid, Liver profiles, X-rays, ultra sound for abdomen and pelvic etc). But all these tests come back normal. I was discharged from hospital after 24 hours.
But i was still having breathing problem and weakness in chest, so i went to see another doctor who asked me to have echocardiography test and even that came back normal. Every time when i get breathing problem i use to get very anxieted thinking that my breathing would stop. The problem continued for many months and i've lost all my confidence.
In aug 2015 i quit my job and decided to take rest, thinking that i might get healthy again. But i couldn't and my health problems continued. During my stay in home i also had some sleeping issues(may be i was thinking too much about my health). I have visited a psychiatrist thinking that it could some chemical imbalance in the brain that is causing breathing difficulty and weakness inside chest. The psychiatrist told me that checmical imbalance causes similar kind of symptoms and he prescribed me Paroxetine 12.5 mg and Clonazepam 0.5 mg. My sleeping issues gone, but breathing issues continued though. After few months my Psychiatrist stopped prescribing clonazepam as i was not having any sleeping issues, but he continued prescribing Paroxetine 12.5, though there was no improvement with my breathing problem, i kept taking it.
Then from April 2016 i started having pain in my lower back that radiates to both my legs, but mostly on right leg. I have visited a orthopedic doctor who prescribed me some pain killers and taught me some exercises. But i kept doing exercises but no use. Also pain moves from place to place. for example some times its in the lower back, and sometimes its in the sides of my buttocks or middle of the buttocks.
I have also had hormonal imbalances test(Total testosterone and SHBG,TSH,FT4,FT3,Cortisol level) last month and all the results came back normal.
My current situation :
==>Breathlessness and weakness in chest.
==>Pain in my buttocks and in legs(sometimes it gets worst when i walk or sit longer)
==>dizziness and feeling of faiting.
==>Brain fog.
==>Anxiety and depression.
==>I also feel weekness in my both hands.
My psychiatrist told that he would change the antidepressants from ssri to snri. I'm worried about the new antidepressants because of the side effects.
My question is does neurotransmitter imbalance really cause above symptoms? If so, then how to find which neurotransmitter is causing the above symptoms? are there any tests?
The current antidepressent (Paroxetine 12.5) doesn't fix any above symptom except it is working for sleeping.

Thank you doctor,
Today i have visited my psychiatrist and he prescribed Denlafax-50. I see it is SNRI drug. Are there going to be any side effects ? The tablet shows Desvenlafaxine 50mg, Does it going to increase more serotonin in the brain? last time when the doctor increased Paroxetine to 25mg i had severe side effects like nausea, confusion.
Now this drug shows it is of 50mg, so i'm little worried that it might cause same side effects again.

Thanks in advance.