Is it possible to develop ALS after 2 years of twitching, based on a dirty 2nd EMG?

[GaborBP]

I'm a 29 years old Caucasian male working as a programmer, my father developed bulbar-onset ALS at the age of 54 and passed away after 2.5 years. He had non-affected parents and 8 siblings, his condition was tentatively attributed to a heavy head trauma with brain contusion 14 years prior to the illness, and possibly lifetime diesel exhaust exposure (there was a study about truck drivers more suspectible to SALS). In August 2015, I started to feel a heaviness/subclinical weakness in my left arm and hand, which was worse in cold weather, but mostly gone into remission by now. Shortly after that, I started experiencing bodywide fasciculations, for which I had exams in September 2015. The neurological exam was unremarkable, the EMG found no abnormality in the left opponens pollicis, abductor digiti minimi and tibialis anterior. I also had negative SOD1 and C9orf72 tests.

The fasciculations waxed and waned, slightly controlled by Carbamazepine and Diazepam, but somewhat worsened in the last few months, which I attributed to work-related stress. I have a hot spot over my left eyebrow which has been twitching almost non-stop for 2 years. Sometimes when I twitch, I experience an electric-shock like sensation going down the side of my neck.

I have high arches (inherited from my mother) and I also experienced mild sensory symptoms, essential tremor, joint cracking, migrating back pain (scoliosis/sitting for long in an abnormal posture?) a spontaneously resolving right abducens palsy, and moderate trigeminal neuralgia-like episodes (every 3-4 months, moves from one side of the jaw to the other). Cramps were rare (once every 3-4 weeks), nightly and always happened in the calves. Prior to the onset of my disease, I had (mostly morning) nausea and vomiting for 3-4 years, which resolved appr. when the other symptoms started. I also had (and has) proctalgia fugax for years. My cervical MRI in 2015 was unremarkable (scoliosis), my cranial MRI in 2016 showed a DVA and a non specific periventricular occipital T2 lesion.

In December 2016 I had a NCS, which found a mild carpal tunnel in my right hand and mild generalized temporal dispersion suggestive of demyelination. I had a clean immune test, incl. anti-GM1. In July 2017 I had a 2 week episode of left shoulder stiffness, which was found to be not spastic in a neuro exam. I also had a 2 day neck stiffness shortly after that, which I attributed to my lifestyle and work. In the last few weeks, I started to feel bilateral knee stiffness/"wobbling"/"jelly-like feeling" (worse in the left side), which causes tremor when standing up after sitting for long. However, I was still able to hike 10+ miles in an difficult terrain even though I'm not athletic. What's more, my legs felt somewhat better after that.

A follow-up EMG in this September picked up the following abnormalities, which is summarized by the EMG neurologist as "minor abnormalities of uncertain etiology"
Mild amplitude reduction and temporal dispersion (worse than in 2016) in the left peroneus with decreased F-Wave persistence.
Increased insertional activity, CRDs when moving the needle or percussion, fibs and psw in certain needle positions in the left tibialis anterior. Mild subacute neur. lesion.
Incr. ins. activity, fibs when moving the needle, no spontaneous activity at rest. mild polyph. MUP in the left deltoid. This muscle was considered normal (?) in the summary
Incr. ins. activity, fasciculations, fibs in multiple needle positions, active partial denervation in the left frontalis.
Amplitude increase, fibs and fasciculations in some needle positions in the right longissimus thoracic. Subacute neur. lesion.
Interference pattern/recruitment were otherwise normal.

My questions/concerns about this EMG are the following:
My understanding is that cranial and paraspinal denervation are highly specific for ALS. In that sense, and given the other findings, how valid are the "minor" and "unspecific" terms in the EMG summary
My understanding from the poly MUP in my arm EMG that it's indicative of reinnervation. Is it possible in ALS to practically regain all strength for months in a muscle?
Do the non-MND symptoms point to something or are they appear to be incidental findings?

My intepretation of the EMG is PMA/LMN-dominant ALS, but the onset of my symptoms, the lack of clinical weaknes, no athrophy (I have a dent in my right gluteus, but my neuro said it was pressure lipoathrophy), improvement in my arm and other symptoms seem inconsistent.