im going crazyy please help me out FTM

my almost 2year old son has been doing this for the past two three weeks...in the beginning i thought he was just doing it cus it was new to him but nope i think something might be up and im confused there is days he doesnt do it but when he does do it it seems odd to me ive never in my life seen some baby or toddler doing this... anyways he lays on the floor on his tummy and with boy feet he pushes them together he does it for like 15mins and gets all sweaty his private gets huge and red :( most of the time he doesnt wear a diaper either and i dont see a rash im soo confused why he does this.. or he gets on top of a box or toy and goes crazy like he's scratching his private part he will get all hot and sweaty and falls asleep I've made an appointment but i feel like the PED might think im crazyy and wont give me answers to this please help i can tell this isnt normal...even when he wears a diaper he does this i thought maybe the diaper bugged him so i been leaving it off just to clear things up