My SPD 4 year-old needs blood tests and this will panic him. 100th percentile in size and very strong. How should I approach this with him?

My 4 year-old has SPD. He's 100th percentile in size and he's very muscular. When he has a sensory meltdown, he can be very difficult to control physically. Fortunately, he mostly melts down at home and I don't need to restrain him, because he mostly just screams. We keep the toddler away from him, so she doesn't get hit, the screaming eventually passes (in 40 - 60 minutes) and that's that.However, when he hulks out in public, where I actually need him to do something like get in the car or have blood drawn, we have a serious problem.So, I would love some ideas on how to help approach this, especially from other SPD parents who have been through this.This is my plan right now:I was going to tell him that we are going to see some nurses. He will immediately ask if there will be needles. I try very hard not to lie to him, because trust is important with him. He has horrible anxiety and struggles to trust anyone or anything. So, I was going to answer "maybe." If I tell him yes, he's going to start revving up to panic immediately. I'd follow up with, "If there is anything ouchie, we will get a Thomas mini (his favorite treat) afterwards." I have 2 Thomas minis that I can give him afterwards. We can play his favorite TV show on my phone, but, honestly, he has a laser focus on things that he doesn't like. He's not going to let us distract him. I was planning on packing a lollipop, because I know that having something like that while being stuck with a needle can help with panic and pain.The last time we did a blood draw, I had him in my lap and 2 people had to help me hold him still. To complicate things further, my family has these really tiny blood vessels, so he had to be stuck multiple times to get a vein (me and my grandmother have the same problem... takes many tries to find a vein for an IV, etc.) and then he wouldn't stay still so they struggled to get enough blood. They always struggle to get enough blood. I really need him to stay calm. These blood tests are important. He has some serious health problems and we need to figure out what's going on.He's somewhat sensory seeking (also avoiding in some respects), so maybe I could give him a foot/leg massage before I spring the news. Sometimes that helps calm him.So yeah.... any ideas about how to improve on my plan? What helps your SPD kid? via /r/Parenting http://ift.tt/2mhYzAP