That after the first week of the shots my rear got used to it. It became less painful and the bruising got a lot better. And I bruise very easy. I think a big part of it was my hubby got better at giving them to me and massaging the area after!
And I actually seemed to get less bruising when I didn't do the heat after. In my am shots I was always running to work, so I would ice but wouldn't be able to heat.
I hope it gets better for you soon!