Daily random shocks throughout body

Hoping someone can give us suggestions of things for us to test for.
Two of my kids, one boy age 15, one girl age 11 get random shocks in their bodies everyday. The shocks go straight through their body from front to back. It does NOT run along a nerve. There can be just one or up to about 10 in a row. It can be so painful it makes them moan out load in pain or ones they barely feel. They last for just a second or two. The shocks happen everywhere on their bodies, mostly on their chest and rarely on the head.
My oldest son has seen a Cardiologist and a Neurologist where he had tons of tests done showing absolutely nothing. He had a MRI of the Brain, EEG, MRI of the Spine and EMG on the arm and leg. All of his blood work came back normal except the TSH said slight elevation of 5.69. But he retested and it came back normal. The following are some of the tests that he did:
A & A, CBC blood count, CMP, Full Rate Count, Heavy Metal Screen, Lyme disease, Magnesium RA Factor, SED Rate, T3 total, T4 Free, T4 Total, TSH and Vitamin B12.
The only thing that I can see that these two children have in common that my other five do not have, is that they both often get motion sickness but we have stopped that with Peppermint oil. They also both also get light headed and have small headaches etc. when the exert themselves in sports. (They are very competitive and always give more than 100%...saying that so you understand that they are really pushing themselves when they get light headed) If anybody knows of some things we can look into as to what this could be I would greatly appreciate it. I think the thing that seems to be different, is that the shocks again, always go from the front of their body straight out their backside.