<human>: Could you distill the essence of the text into 1-3 sentences?

Last night, my girlfriend and I had our 11mo old rescue beagle/terrier (we've had him for 6mo) at the dog park we've been to plenty of times. He had been running and being chased by other dogs for about 12 minutes. After getting some water and resting, we decided to walk with him around the park off leash, something we've done plenty of other times. As we started walking, he started to limp off his back left leg, ran a quick circle with his tail between his legs and came right to our feet, not wanting to move. We noticed something wasn't right so we picked him up and left to go home. After getting home, he was very scared and unsure of everything. He stood in one spot in the apartment for about 10 minutes until I moved him. He wasn't interested in toys or treats. After about 30-45 minutes we got him to eat a few treats and he eventually ate his dinner on his own. 

Upon taking him out before bed last night, he seemed fine, we got about halfway down our street and he hopped his back end and seemed all scared again and would just lay down in the grass. He did pee, but after that he didn't want to move and I had to carry him back to the house. He slept fine all night and isn't showing any signs of injury either.

This morning, he was the same outside, he peed, but I couldn't get him out of our driveway. He just laid down in the grass, tail between his legs, sorta limping. We inspected him all over and didn't see any scratches, cuts, bites or stings. He's usually very playful, happy, curious puppy, so the way he's acting is very uncharacteristic of him which has us concerned. 

Any idea what happened? How can we get him to feel more comfortable outside so he can do all his business?
<bot>: incident at the dog park has our pup scared of going outside for any reason. How can we make him be comfortable and confident outside?