It’s so hard when they are like this isn’t it? My first was like this and she still is now at 12 years old tbh. Meanwhile my 3 year old will be ok ish if we chat about it / role play beforehand and promise to buy a treat afterwards. With our extra sensitive children we just have to be there for them and validate their feelings but remind them why we are doing things I suppose. Good luck with the injections x
Reading books about new experiences has helped my daughter a lot - sometimes literally for months in advance! Also seeing me do things first makes a big difference: e.g. watching me have a dental checkup, getting my flu jab, and having a blood test. I also talk with her in detail about what will be happening so that she’ll be prepared - sometimes even playing with her toys and acting out the new situations, which I think helps her feel more in control of it all. Hope that’s helpful, I know how hard it can be!