The Rules of Professional Conduct govern attorney communications with clients represented by other attorneys. Rule 2-100(A) provides the general rule: "While representing a client, a member shall not communicate directly or indirectly about the subject of the representation with a party the member knows to be represented by another lawyer in the matter, unless the member has the consent of the other lawyer."
However, there are exceptions to this general rule. Rule 2-100 says "This rule shall not prohibit:....(2) Communications initiated by a party seeking advice or representation from an independent lawyer of the party's choice.
The use notes to this rule, related to Rule 2-100(C)(2) says the following: "Subparagraph (C)(2) is intended to permit a member to communicate with a party seeking to hire new counsel or to obtain a second opinion. A member contacted by such a party continues to be bound by other Rules of Professional Conduct."
You may seek a second opinion from another attorney, and that attorney is ethically allowed to give you a second opinion about your case.
Here is the rub. You will likely have to pay that attorney a good sum of money to study your case and render that second opinion. Any attorney willing to opine about the value of your case without fully understanding the specific facts and circumstances of your case should be doubted from the outset. Every case has individual details that make it better or worse.
Good luck to you.
This answer should not be construed to create any attorney-client relationship. Such a relationship can be formed only through the mutual execution of an attorney-client agreement. The answer given is based on the extremely limited facts provided and the proper course of action might change significantly with the introduction of other facts. All who read this answer should not rely on the answer to govern their conduct. Please seek the advice of competent counsel after disclosing all facts to that attorney. This answer is intended for California residents only. The answering party is only licensed to practice in the State of California.
The relationship between the lawyer and you is one of contract. Accordingly, you may seek a second opinion without breaching the fee agreement. In any event, I suggest you set up a office conference with your current lawyer and voice your concerns. The fact that your attorney agreed to represent you in the matter should be some indication of his belief in the merits of your case.