I simply suck on a few granules of course sea salt three or four times a day. The first time I fasted (7 days) I had similar troubles. Subsequently I read The Ketogenic Bible, and this time around (9 days in) I haven't had any problems whatsoever.
First off, HAT's OFF to you. Good on ya for getting going. Whilst I currently check in at 232 lbs, I know how you feel and my heart goes out to you. I'm kicking off with my Keto diet (again) today and (this time) nothing is gonna stop me!
I found a good book on the subject, The Ketogenic Bible, which I highly recommend reading.
Keep us posted on your progress and I'm rooting for you.
For anyone who might read the comment above the above comment. It should be noted that this is the norm for the latest keto (The Ketogenic Bible) or weight loss on keto although it's not what this subs out of date information recommends for weight loss.
The idea that protein is a goal is a mythical concept contradicted by most keto specialists today. The right amount of protein, as recommended by Dr. Jacob Wilson MD, Ryan Lowery PhD(c), Dominic D'Angelico PhD, Nora Gedgaudas CNS, NTP, BCHN, Dr David Perlmutter MD, and a host of others, is equal to 0.6g to 1.2g of your target Kg body weight, and not the overdose of Protein recommended by that one-size-fits-all online calculator promoted above.
The correct amount of carbs is an individual number which only you can figure out for yourself with personal experimentation. For me personally, that is between 5g to 10g of carbs a day.