Hi Analei and welcome to the forum!

Yes, that "fuzzy" headed feeling is quite common for the first 3-5 days. Usually it's a combination of carb withdrawal and your body getting used to burning a new fuel source (fat!). Some have reported having it a bit longer, but it usually clears up after the first week. If it doesn't, then there may be some other things going on such as not eating enough, not drinking enough water or a mineral deficiency such as low potassium or magnesium.