I am not too much of a fan of the keto diet but it works well for a lot of people. In fact guys like Dave Palumbo of rxmuscle loves that diet and subscribes it to all his clients. Now he does tailor it to the needs of that specific person but the keto factors are always there.
If your getting dizzy it might be that your lacking certain nutrients that you would more commonly get from the carbs. Some of these can be supplemented with vitamins. It also depends on how heavy your lifting, if your going heavy you may be pushing yourself beyond your limit and taxing your nervous system. Now that is not overall a bad thing, that is where real growth and strength gains take place. Trust me when I get into really heavy squat or deadlift I have to sit down after. Especially squat!
Arti I agree fully, I am a fan of doing the Big 3. When you look at my work outs they tend to revolve around those. Everything else is pretty much an accessory based around the bench,dead or squat. I know several people who have done p90x but did not get the "beach body" they wanted. It did give them a decent base though to when they decided to pick up the 3 and get in a gym.
Serious, your progress is very cool and I am always glad to see someone transform themselves as you have. Keep up the good work!