Insulin injection issues...

I am having a strange occurrence with my insulin injections and wanted to see if anyone else was experiencing this and what their doctors did to help?

I was diagnosed with GD at week 7 and knew that at some point I was going to have to go on Insulin for the overnight due to my high fasting numbers. I started at 10 units and since have been increased to 28 units. All was fine with the injections but once I hit 20 units I started to get large red bumps that were very itchy showing up at every injection site. I rotate my sites and have not used the same spot twice. Has any one else had this issue? I follow up with my perinatal on Monday but wanted to throw the question out there.