A pain point is not "We do x for y like z does for a" (especially when z is showing no growth).
A pain point is the identification of the problem a specific customer has to which you can apply a solution that removes this problem.
In identifying the pain point, you need to validate the entire scope from the user's perspective - their entire perspective.
What I'm trying to say is that you need to be very, very clear on what benefit you are bringing to the user, what other options they have, and most importantly whether or not the "pain point" is worth their investment in finding a solution.
I say the last point because I fear it may be directly applicable to you and your situation, and you even provide the evidence to support this in your comment.
Ask yourself this question: Why doesn't menupages.com appear to be seizing the growth opportunity?
I don't have the answer for that question, but in order to be successful, you need to confirm that the answer is not - in any way - related to the market, or lack of one.
It is highly possible that getting menu content online is just not enough of a problem for enough people to be worth investing in the solution you have developed. I know I eat out a great deal, yet see no use for this particular function beyond casual knowledge. (i.e. if I couldn't find a menu, I'd probably just go to the restaurant anyway).
I think, honestly, you should backtrack to the start point here and go through the process of nailing the customer identification process. It's very possible that my hunch is incorrect, but you need to find out - exactly - how if you are to be successful here.
Good Luck.