What do I do next?

This is not a case most lawyers would consider, especially as a defamation case, unless it was UNDENIABLE that the allegations were completely fabricated. Just because you were found "not guilty" of a criminal charge does NOT equate to innocence nor does it avoid the "where there is smoke there is fire" aspect of public opinion in general. All you can do is simply keep contactoing lawyers until you find one that might be interested that you can afford to hire or that you satisfy yourself that its not a viable case to pursue. Understand however, that unlike a criminal trial, where you have 5th amendment privilege - you DO NOT generally have that in a civil trial postured as yours would be - which can be problematic if the defendants dig deep in to your past and internet history and might find unsavory issues or events. I point this out because people often fantacize that people being sued will not find out other details that might be embarrassing or humiliating and the scope of the civil discovery is often far greater than that in a criminal case.