Sorry to hear it's still going on for you. At the moment it's pretty much gone. The best it's been in a long long time for me. I remember reading in one of the threads I posted in (might even be this one) that a guy said hydrocortisone cream is the solution.
And stupid fucking me, I actually have a tube of it from a couple years ago when a doctor diagnosed me with mild eczema and acne. What's more, I have a similar but stronger product I believe called eumovate, again which he prescribed for the same reason (one to use in morning, on at night).
I can probably say with a lot of confidence, this helped. I also like to use cold green tea just on the patch to help soothe it (I read up about this, basically something about red skin, green products counteracts red, and voila)
My acne seems to have calmed down recently a lot, even though I've had a fair few unhealthy weekend and stuff recently (eating rubbish, being in rooms with several smokers etc)
It's funny you mention the hammer and arm baking soda toothpaste. I feel like such a twat for admitting this, but I used to use that on individual spots I got, which were always around my mouth and jaw. I'm guessing I shot myself in the foot there and have no excuses, but it probably caused my problem.
So that's what I've been doing the last month or so, and I think I could be finally over it. Unless it decides to comeback randomly of course!
Good luck with your problem, hope I helped somewhat.