I've recently gone through a similar experience. My horse is extremely nervous by nature and we have, over the period of two years, worked up to going on short trail rides with him staying very calm and under control, even in potentially spooky situations, but about a month ago a deer spooked him on the trail and I got thrown. Now we are back at square one for both of us, the spot where I was thrown is in sight of my arena and even riding past it in the arena will cause him to look and tense up slightly at the beginning of each ride. His nerves are definitely feeding my own nervousness, we have gone on a couple trail rides since I was thrown and he hasn't had any major spooks, but it isn't the nice relaxed hack out we were both enjoying before. It feels like we are both on high alert, and I know when he is in that mode it doesn't take much to set him off.
So, my advice to you is to be very aware of both your emotions and your horse's at every step of your ride, if you feel nerves building in either one of you, back away from that spot and ride in a circle until calm returns. Circling near a spooky place has the effect of approach and retreat, one part of your circle will be near the scary area, you teach the horse it is OK to get near it, we will leave soon, by doing repeated circles the horse gets more comfortable and will eventually be willing to go through a scary spot because they don't feel like they are going to be "trapped" there. The more nervous, the smaller the circle should be, as confidence returns, grow the size of your circle.