Not reassured by Neurologist

Hello
I am a 27 year old male and for the last number of months I have been suffering from some very worrying symptoms. It all started in July when one day I tried to take a drink of water and my hand and arm started to shake to the point where I couldn't put the cup to my mouth. This passed after a few hours but something didn't feel right with my hand. It was a week or two later when I noticed the muscle at the base of my right thumb had completely disappeard. I then noticed I was getting continuous muscle twitches in my legs and also a kind of ripelling when I stretched them. I have had MRI of spine and back which showed nothing. I then had my first of 3 EMGs. The first showed only wasting and denervation to the APB muscle only. As this test did not include my legs I was sent for another test this time doing more muscles including my legs, back and tounge. This also came back with the same result.(isolated denervation but not picking up any of the fasculations I had been experiencing). The first neurologist said he did not believe it was MND but wasn't sure what was causing the symptoms. I decided to see a specialist privately in London who deals with MND patients. I had another set of EMGs done and this time the fasculations were visible but still only isolated denervation to thumb muscle. This neurologist has said also that my physical exam and tests did not support a diagnosis of MND but more tests should be carried out including another Neurophysology exam and more MRIs and a MR neuronography what ever that is to look for something called multifocal motor neuropathy. I am very worried that this still could be MND and am just wondering if anyone has had EMGs that didn't support MND only to find out they actually had it. The muscle twitching has got considerably worse and now my back and arms are twitching .Also my left calf feels very tight and is a lot smaller than my right. I understand this can sometimes be the case but I ran two marathons for charity last year and never had issues before with my calf muscles. I am yet to receive date for next set of tests. Any feedback would be greatfully appreciated.