Help! Puppy is scared of going on walks after tripping

I have an 11 week old puppy that came home with me one week and two days ago, so maybe I haven't given this enough time. I've been taking him on short walks to a park right beside my house at least once a day, which he has done fine with until now. Two nights ago, he was chasing my husband in the field of the park, and it looked like his front leg went into a hole and he tumbled forward, let out a little whimper after he got up, and walked with a limp for maybe ten minutes (I ended up carrying him home because I was scared of him putting weight on it). He seemed totally fine after a few minutes, slept a little when we got home and hasn't had a limp since. But now he's TERRIFIED of going to the park. He does ok when we start the walk, but once he sees we are getting close to the park he tries to go back. If we make it all the way to the park he fights against the leash to try and run back home. What should I do? I hate that one bad experience has made him so scared of something he liked before. A similar situation happened with three steps outside down to my driveway, and now he's terrified of any and all stairs. I just want him to be comfortable! Thank you for any advice!