We had a similar situation in our office that is shared between developers, testers, and the relatively small help desk. When the help desk got a question they couldn't answer, they would ask a developer or tester for assistance. Over time, the help desk people asked fewer questions overall but they began asking the same person all the time because that person was either the most helpful or maybe the most pleasant to deal with.
That worked well for everyone but that one helpful developer that was getting all the questions (some of which could take a while to deal with). He was being very helpful, but not getting much development done.
We ended up instituting a developer of the day that became the go-to person for all help desk questions. If question was more appropriate for a different developer he would refer the question to them, but the help desk had to start with the developer of the day.
We rotated the responsibility between 5 developers. Each developer only had one day per week of major interruption and the help desk couldn't just wait until it was their favorite's turn because that could be several days off.
You should take it as a compliment that everyone respects your knowledge and is comfortable coming to you for help. That really is huge. Now you need to help your teammates grow in their expertise and ability to assist coworkers.