Not sure why there werent more posts here to help you.. I know the thread is old, but wanted to say (type a few things)
I love catching swarms and regularly put out multiple swarm traps.. many of the locals know me and call me if they find a swarm or a feral hive..
I never disturb a feral hive, and often FEED them when we have bad times.. My hopes are to capture swarms from those hives...
Now.. when a hive swarms there are several reasons.. primary swarms take the old queen with them. secondary swarms may be virgin queens..
I have experienced just as you have experienced.. booming start, only to dwindle and fade away.. As already posted, it can happen.. if your queen started and then failed. if the virgin went on a mating flight and did not return, or if a neighbor sprayed his garden with pesticides.. etc etc etc... MANY reasons it can happen.
Having two to four hives (or more later on) gives you resources in these situations.. adding frames of brood to keep them strong and allow them to make ANOTHER new queen. swapping places with another hive so the field bees return to that one etc.. In a worst case scenario.. you can take the dwindling hive with no queen and combine it with one of your other hives.. then SPLIT that hive in the spring to refill your empty hive...
Stating with one hive makes it hard to judge the condition of a single hive. as stated.. they WILL dwindle.. IF.. that swarm was an older swarm that couldnt find a good place to take up residence.. they may have been without a home a couple of weeks, making the bees too old to carry on long enough to restart.. You stated they were on the ground by the road? Was the queen damaged as the refusing beek said? thats where adding brood would help with new young bees and supercedure cells.. He SHOULD have helped you irregardless!!!
You didnt do anything terribly wrong... I find it a bit disturbing that ANY beek would refuse to help you.. those in this area help each other when they have problems. I have taken brood frames to neighbors. I have employed my vac to help them do cut outs. I have spent an entire DAY trying to get three hives apart and re situated that have not been touched in three years... All in repayment for the aid they gave when I started.
There may be extenuating circumstances... no time due to work, sick, etc... but Otherwise I find NO excuse for a beek to refuse aid to another. ESPECIALLY one just starting out. Makes me glad I live where I do...
PLEASE restart, and do it with a couple of hives two or even three or four. I started with four, dwindled to two, then moved to five from local swarms, and have grown from there. Losing a hive sucks.. but stick with it, and apply what you learn from each loss!