It's good that you received a copy of the by-laws and rules and regulations for the complex when you purchased it. The rules regarding leasing your unit and not having it "owner occupied" should be in there. You state that there are no restrictions but is your copy current or from a few years ago?
It's also good that you have a real estate attorney involved as that is the best person to help you in your situation. Have him look at the by-laws and if you do not have a current one; then ask him to request a copy with the HOA. I would also urge him to get a response from the HOA regarding your imposed fees asap.
Best of luck to you!
Prudential Connecticut Realty
The CCR's are the guidleine, what ever they say.
As to why the HOA would do that:
They probably have a covenant that THEY have to abide, which says that only a certain number of unit may be rentals. If that is the case, then they are between a rock and a hard place because they didn't share this with the residents.
We can't help you; you really, really need a Lawyer.
Good luck and may God bless