I don't think it's a common phase. I would guess it's just a matter of your personal cycles. We all are always experiencing a number of concurrent life, or energetic, cycles all the time. Planetary transits to your astrology chart can give you an insight into these. You probably have something going on that is adversely affecting your Mercury, for example, so you feel unable to relax the mind. Just stay with it patiently, witnessing, and you will no doubt come out the other side. A cycle of this type can last anywhere from a few days to a few months.
You may also have had a particularly beneficial influence going on at the start, which may no longer be with you. This sometimes happens when we start on the path, to give us a taste of what it can be. Don't worry - just keep on. There's nothing you are doing that could cause the symptoms.