Hi jojo - welcome to the forum! It sounds as if your pup may have missed out on early socialisation. Most pups go through a fearful stage at around his age, and if he was on the nervous side to start with, and is now meeting things for the first time, you may need to work quite hard to build his confidence. I would do lots and lots of reward based training at home and out and about - have a pocket full of treats with you whenever you take him out (and a favourite toy if he has one), and sit on a bench somewhere and watch the world go by, dropping a treat to him at regular intervals. You can encourage him to look at you if there is something - or someone - approaching that he might find worrying. As he starts to relax ask friendly strangers to toss him a treat as they go by. Don't try and push him faster than he is comfortable with - there will be umpteen people who will insist they love dogs, and want to pet him, but they will make him more anxious if you let them.
It is also important that he meets lots of friendly dogs, if he is not already doing so. His puppy licence for misbehaving with adult dogs is running out, and he needs to have learned good manners before it does!
If you work on it now, he will improve rapidly. He sounds a lovely boy - I look forward to photos, and hearing about his progress.