MS or Stress and anxiety

I have been having an array of symptoms over the past year, that I have received many diagnosis for. I have seen 7 doctors and have been placed on 5 different medications and my last neurologist says he thinks it is stress and anxiety. I have done extensive research and have yet to link "all" my symptom to anything but MS. If someone can help me link the symptoms below and help me get on the path to help that would be great.

Symptoms include:

Memory problems
Lack of concenstration
Depression
Excessive pain in back and limbs
Dizziness and haziness
Muscle Weakness
Tingling and numbness in limbs of left side
Feeling of extreme heaviness in limbs of left side

The most important symptom that I can not figure out is that when in the heat, whether it is in the sun or inside. All the above symptoms increase 100 percent and lead to left side paralysis and involuntary jerk, twitch, spasm( not sure what to call it) of upper body to one side for a period of up to 30 minutes. Followed by just constant pain til body "cools down". This happens no matter what I am doing. I could be going for a walk with my family enjoying the summer sun or just sitting on the couch in my sisters always too hot house.

The only thing that I found that this relates to is MS. However everyone one of the 7 doctors (2 neurologist) have been very dismissive of MS. I wonder myself because all blood tests and MRI's have come back clean. So the "all in my head" statement sounds real good right now. But I can't bring myself to believe that this pain and helplessness is all in my head.

The drug I am currently on is Cymbalta which I am told is for the depression and pain. However I find that it only suppresses the pain and depression on an everyday level and when the heat is thrown in it is like I am taking nothing at all. When researching Cymbalta recently, I have read up on fibromyalgia which fits a lot but like I said so does MS. I am not a hypochondriac so I don't want to go back to the doctors with the idea of fibromyalgia without facts. Plus if everyone here says stress and anxiety than maybe this is so. I just want my questions answered without being felt like I am being push out of the hospital room for more "important patients".