Desensitisation and Grooming
Find a position that is comfortable for both you and your dog (my Rotties are more comfortable spread out on a place bed, with me kneeling next to them) and work with that.
If you have yet to start grooming/not found a way that works yet, start in an environment that has little/no distractions (i.e inside, with no other pets or people around).
Desensitisation is key! I won't go into the ins and outs of grooming here, but one of our in person or online sessions can help so it is as chilled for you and your dog as it is for me and Giddy.