Petechiae rash in 4 year old

My son, who has mild CMTC in his leg, has been getting a petechiae rash in a butterfly pattern (across his nose bridge and upper cheeks) as well as blotchy rash on his forehead whenever he exercises. I first noticed it about 3 months ago and at that time it was barely noticeable and only every now and then. But now the rash is almost daily but almost completely disappears after he cools down and rests. Like in the mornings when he wakes I don't notice it at all but as soon as he starts running around... There it is! Bright red pinprick spots just under the surface. They seem to be getting more pronounced and multiplying. He doesn't seem flushed as the skin aroun the red spots is pale. I noticed also the other day the the spots were on his upper back but not as pronounced as his face, but didn't see the back rash yesterday.
Should I be concerned? I have taken a few pictures to show the doctor since I know when we he sees him the rash will be barely (if at all) noticeable. Could this have something to do with his CMTC? He also has 5+ ashleaf macules and has been through the ringer with medical evaluations to rule out Tuberous Sclerosis. But genetics came back negative so he is 80% in the clear for TS. I just hope these aren't the beginnings of angiofribomas. ??? Could they be? Or could it be autoimmune in nature? Everything I've read about petechiae says it's urgent... But after 3 months of reoccurrence it doesn't seem urgent but I'm concerned anyway.
My son has anxiety disorder and the doctors always sends him into panic... I hate taking him and he usually needs restraining just to allow the doctor to examine him so if I don't need to worry about this rash I can avoid another trip to the pediatrician.
Thank you for any insights as to what could be causing the reoccurring rash.

[Bhupinder Kaur, MD]

Hello,
Petechiae are pinpoint-sized red dots under the surface of the skin. They are common after skin trauma and viral infections. They should go away in a few days. But if they persist then please consult a physician and get other causes ruled out which include allergic reaction, autoimmune diseases, thrombocytopenia, ITP or leukemias. a comprehensive profile of investigations needs to be done to confirm the diagnosis.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.