I am losing a game. My only option is to check my opponent non stop. I have no chance to checkmate him. I am only hoping to force a draw. Is this proper chess etiquette?
What you are describing is Perpetual Check: http://en.wikipedia.org/wiki/Perpetual_check
It is covered in the rules of chess and the result of such a game is a draw. It is up to your opponent to try and avoid this situation if he thinks he can win. Conversely, if you might lose you should try to get into some kind of draw situation to avoid a loss.
Anecdote: A queen vs. queen, knight, and bishop did the same thing at the club quick tournament last night.
Yes, it is proper chess etiquette. You are not obliged to resign if you have an inferior position. If you can force a 3-move repetition draw by non-stop checks (called "perpetual checks") you definitely should. Players at the highest level have done this.
In fact, we even celebrate some games which have ended with perpetual check by the side with the weaker material. Consider the famous "Immortal Draw" game -
[Event "Vienna"] [Site "Vienna"] [Date "1872"] [Result "1/2-1/2"] [White "Carl Hamppe"] [Black "Philipp Meitner"] [FEN ""] 1. e4 e5 2. Nc3 Bc5 3. Na4 Bxf2+ 4. Kxf2 Qh4+ 5. Ke3 Qf4+ 6. Kd3 d5 7. Kc3 Qxe4 8. Kb3 Na6 9. a3 Qxa4+ 10. Kxa4 Nc5+ 11. Kb4 a5+ 12. Kxc5 Ne7 13. Bb5+ Kd8 14. Bc6 b6+ 15. Kb5 Nxc6 16. Kxc6 Bb7+ 17. Kb5 Ba6+ 18. Kc6 Bb7+ 1/2-1/2
There are several "forced" drawing conditions (other than an agreed draw). In most of these situations, someone is usually behind in material.Basically, a draw occurs when one player can prevent the other from checkmating him, using force.
One is "insufficient material to win." That is, someone has a king and bishop or knight against a lone king, and can't force a win. Another is "stalemate, whereby one player can't make a legal move, but is not in check (and is therefore not "checkmated").
Your situation covers two more categories of draw. The "classic" description of your situation is called perpetual check. That is, you keep the other side so "busy" dodging your checks that your opponent never gets a chance to checkmate you. This also leads to another drawing condition called "repetition of position." That is, if the same position is repeated three times, with the same player to move, it is a draw.
If the chess opponent is not good, then he could lose a queen, then all you now need to do is do a Queen-as-Rook+King checkmate.
However, if he is good, then perpetual check is not an option. You will lose your queen, and get mated by the double Queen mate.
Unfortunately, the only way you will get a queen is by a skewer attack and luck. Keep your Queen close to your King, and guarantee at least a Queen loss for the opponent.
He can perpetually check you. There is no denying it. If he does decide to do so, do the same to him.
Yes, this is good sportsmanship. In fact, the perpetual check is the most important defensive tactic in the Queen+pawn vs Queen endgame.
I can add the following to the previous answers. Other variants of chess have a different opinion about this question. For example, in Chinese Chess, it is forbidden to make perpetual check. See, for example, this resource.
I hope that my contribution is not too far from the topic.