These are some resources I recommend. Some of the below I benefited personally from and their content has informed this guide.
David J. Keuler, PhD. When Automatic Bodily Processes Become Conscious: How to Disengage from “Sensorimotor Obsessions” https://iocdf.org/expert-opinions/when-automatic-bodily-processes-become-conscious-how-to-disengage-from-sensorimotor-obsessions/
The above is a classic and gives a really nice overview of what SOCD is.
Dr Seay’s series of posts on the topic.
Part 1: http://www.steveseay.com/sensorimotor-body-focused-obsessions-ocd/
Part 2: http://www.steveseay.com/ocd-core-fears-body-focused-obsessions-compulsions/
Part 3: http://www.steveseay.com/treatment-body-focused-obsessions-ocd/
This is very detailed and he makes many good points. On the third post, you can actually see my posts from way back in 2012, when I was struggling myself and asking Dr Seay questions!
Hershfield & Corboy, The Mindfulness Workbook for OCD, Ch 14 – Hyperawareness OCD
This chapter on hyperawareness OCD covers more than just body-focused obsessions, although the principles are generally the same. Some good coverage of common thought patterns, triggers and obsessions.