It's easier to tell you what WON'T work in this situation than what WILL, but you've already found out! Teddy's obsession is not uncommon; it's the same obsession dogs can develop with laser lights and even balls...and NO obsession is healthy.
The first thing I'd try is MORE EXERCISE. Springers require a lot of mental and physical stimulation, and they do tend toward more OCD type behaviors than many other breeds...probably because most of them don't get enough of a workout each day. Do you have a treadmill? I'd try Teddy on that, starting gradually and working up to about 20-30 minutes a day. I'd supplement that with leash walks and obedience refresher training that you turn into a game. Try him in a Rally obedience class, which would be held outdoors this time of year...with shadows, signholders all over the ground, lots of dogs and people, etc....all to desensitize him.
You might also try Rescue Remedy or similar non-Rx homeopathic calming agent. Rescue Remedy is made with bach flower essences and is very effective with some dogs in taking the edge off. You can find it at some pet stores and health food stores.