HRT allergic bumps after injections

Hi! This is my 4th month on HRT. At first, I never had bumps from injections. However, lately it had been happening and happening more and more. It is just annoying, but it doesn't hurt. I injected yesterday, and today I have a slightly larger than mosquito bite sized bump on the injection site. This is the largest it has ever been. Is this normal? As I said, it doesn't always happen. I only inject 0.08ml EEn (with MTC oil) into the abdomen.