Emirates has a baggage policy as follows,
Apparently, I have a carry on baggage of size (25+33+64)=122cm.
What should I do now?
Emirates is very strict about carry-on allowance and they check quite often but not always. So would not risk it without a backup plan. Weight is strictly enforced too, by the way.
Your bag exceeds two dimensions by 5cm which is not much but if they make you try it in the sizer, it will not fit if it is rigid. A soft bag though, if not completely full, will fit, so check if you can squeeze it to the required size, even the official measures are larger. If it does, chances are that you will be good to go.
Now, if it does not fit, getting a new bag within the limit is not that difficult. The size Emirates allows for carry-on is fairly common among airlines (8" x 15" x 22"), although many use 14" instead of 15". Look for a bag within that size. Now I had a lot to carry and Emirates is one of the few airlines that does not accept a personal item in addition to a carry-on, so I asked this question earlier this year. Answers do have some good options but I could not get one in-time from Ecuador, so I had a custom-bag made to the exact maximum allowed by Emirates.