My son (just turned 5) started playing with his mouth with his fingers about 3 months ago. It began as something he did a couple times a day and has become more and more constant. Basically he fills his cheeks with air and blows it out of his mouth while running his fingers over his lips.
In addition to doing it more often, he has gotten better at it - meaning louder.
I keep waiting for him to start playing a tune.
I alternate between being really concerned about it and not worrying about it at all. It has become more frequent as school and can be a disruption there.
Asking him to stop of course does no good. I know he is seeking input and can't fully control the need to do it. We have tried gum as a different form of input - he just does it with the gum in his mouth.
Anyone have other suggestions?

I don't have any suggestions but sympathise as my 5 yr old has started eating his fingers and clothes he constantly makes noises. I said to my daughter it's like having someone with turrets. (not that I am taking the mickey here you understand) it's just he drives me potty shouting out when walking round shops or going to school.
He is always drawing attention to himself. If people take no notice he gets worse or starts spinning. This as you have said has only just started. He did, when young, chew things but we somehow got him out of that, alas not for very long.

Am hoping you get a reply to this post as I thought it was just him.

My son, has SPD and he also has tourettes. His is very sporatic, and ever changing. Mostly - you would never know that he has tourettes - because his worsens when he is getting sick, or if he is having extreme anxiety. Tourettes, like SPD - is far more complex than what the general public understands. I recently watched a documentary called "different is the new normal" and it follows a boy from very young - to college age. I have it saved for my sons next round of severe ticking, to show him. He is 12, and was diagnosed a few years ago. Tourettes is not just a vocal situation. In this documentary - it is noted that tourettes starts at around 5 years. I have already made my husband and older son watch it, so that they understand he cannot help it. I highly recommend watching this. The overlap of SPD, ADHD/ADD and tourettes symptoms are astonishing to me.

My son used to make various sounds when he was younger (4-8 yrs). He's gotten much better and doesn't do it nearly as often as he used to. I was going to say he stopped all together now, but he might make sounds now and then but stops if you ask him to.

By 4th grade, he really became conscious of other people and what others thought of him, so it got a lot better last year. He's 11 now, finishing 5th grade.

My youngest daughter comes off with some weird noises as well. She makes noises very similar to your son's. I have found that the best thing (That works for my family) is just letting it run it's course. Yes, it can be very annoying at times and she likes to do it at odd times, but it has actually decreased since I have stopped acknowledging it.

She is only 2, so I'm sure there will be more noises I deal with. But the less I acknowledge them and just let her explore with making noises, the less common the noises are.