I vape mostly 7mg nic DIY eliquids now. When chain-vaping, I'll vape maybe 8-10mL a day. I've never felt dizzy, nauseous, etc. at that amount each day.
I DO get funny, weird hiccups sometimes though. It's only happened if I've gotten a tiny bit of certain eliquids on my finger, and lick it off rather than wipe it off with a tissue or paper towel. I think I have it narrowed down to eliquids that contain VBIC and/or custard. They're not like a real hiccup, but sort of like a small spasm in/around my voicebox. Sounds more like a frog croaking than a normal hiccup. As soon as I take even a small swallow of Coke, coffee, or just water to rinse it away...they're immediately gone.
By the way...for normal hiccups that you want to stop - just eat even a tiny Tic Tac or some other little piece of candy, and they'll be gone. I used to keep a little box of them in my desk when I taught school for 30 years. Any unstoppable hiccups were silenced within a few seconds, with just 1 Tic Tac. Works like a charm!