I'm in the same boat. Another thing I've realized is that while my interest may jump between half a dozen different things, if I just let it run its course, it tends to circle around. I.e. I don't leave an endless trail of projects in my wake, I revisit different ones as that interest rekindles. But before I realized this, I would be really hard on myself about switching, trying to force my interest to sit still, which really just killed my interest in all of them.

Bottom line: don't try and pin down your interest, open up to it and let it run its course. The course may not always make sense but it knows what it's doing.