For me, side effects of too much nic and having a nic withdrawal is almost the same, minus the nausea. It might be different for others.
I get the jitters when my blood sugar gets low. I have normal glucose level but I am somehwat of a gym rat ever since I quit analogs, so when I push my body hard, wham, I get the shakes, and light-headed. Only reason I mentioned that is because I noticed you said you run regularly...
Oh, when I see a vape gear I really like, I get the cold sweats.