I wrote this as a response to another mom on our local email group about her 3 year old son with Down syndrome starting to have terrible tantrums.
Well, we didn't go thru exactly this, but I'll share some thoughts anyway.
Becca went thru a challenging stage at 3 where she was physically aggressive - hitting kids over the heads with drumsticks comes to mind, and some biting. It eventually passed and 2 years later when she entered kindergarten I wasn't worried about it. Anyway, it started the same time she finally started walking, and we think there was a connection.
Random thought #1 - everything takes longer with DS - walking, talking, potty training, going thru stages including tantrums.
Random thought #2 - developmental delays include developmental stages like tantrums. I remember talking to Becca's teachers about her still hitting when she was 4. So instead of the terrible 2's, it might be the terrible 3's (or 4's).
Random though #3 - Like with any kid and new behavior issues, has anything else changed in his life? Did he just start walking? Are you working on potty training? Any family changes - moving, divorce, change of schedule? It's summer time, so is he no longer in the same school setting he was in before?
Random thought #4 - How is he currently communicating other than tantrums? Is he speaking at all? One word? Two words? Does he sign? If he has had a mental growth spurt with new thoughts/feelings of independence, but is unable to communicate at the new level he may be really frustrated. For example maybe before he was happy to eat whatever you gave him, but now he wants the chocolate ice cream specifically instead of vanilla. If he has no way to communicate 'chocolate'...
Random thought #5 - He has you wrapped around his little finger. (maybe) But whether he does or not, you always have a choice. You have to take a deep (really really deep) breath and recognize that doing what is best for your child is more important than meeting other people's expectations and reducing your own embarrassment. Every time he gets what he wants because of a tantrum, you have dug the hole deeper. When you are trying to get out of a hole, stop digging.
Random thought #6 - Positive reinforcement for good behavior & practicing alternative communication. The antidote to #5. Find times, however minuscule, where he reacts in an appropriate way and totally praise him over the top. Try to make more of those moments possible (is he best behaved at Grandma's house? At the park? Go there and praise him every opportunity you get) What words and/or signs does he need to be able to communicate better?
Random thought #7 - Stop drop flop is definitely a DS thing. Still dealing with that here and it's not easy with a 50 lb child. Licking is definitely a DS thing. Praise God, Becca is over that.
Random thought #8 - Sensory issues. Christian, Denise's son, needs extra gross motor stimulation - think bear hugs and jumping up and down hard. I'm not an expert on this, but you could ask the PT or OT about it.
Random thought #9 - "It's not me, it's her" This is my mantra as I go thru the ordeal that is brushing Becca's hair every morning. I used to get really overwhelmed and angry every morning. After some introspection, I realized I was frustrated at my inability to control the situation or make it better. Realized I can only control me and I'm doing the best I can. She screams, I talk softly and we get thru it.
Good luck, eventually this too shall pass, hang in there!