Anybody have any tips for healing razor rash/shaving bumps?

So a few months ago, I stopped shaving under my arms, after I realized that I wasn't getting any extra satisfaction or confidence from shaving them. My skin is extremely sensitive, and I always, always, always got really uncomfortable razor bumps from shaving my underarm area, no matter what shaving method, razor, or cream I used. Thus, one day last fall I just quit altogether, and was quite happy.

However, I had an appointment to get a tattoo on my arm touched up as a birthday present last week, and I had to shave prior to being worked on by the tattoo artist (the tattoo stretched into my underarm area). I bought a brand new razor and shave gel and shaved the night before the appointment, and my skin has been on fucking fire ever since. I've never had a rash this bad before, it's all over my underarms on both sides which makes me sure that it's not just simply tattoo related. I've been using an all natural deodorant from Lush and have been putting coconut oil on the affected areas before bed which seems to have helped some, but I've never had a rash last for over a week like this one has. Plus it HURTS.

Does anybody have any tips or remedies?