Is there a good resource for helping to discern the cause of pain / soreness?
It sounds like you want a web site similar to WebMD that you can put in symptoms and get an answer. I'd recommend against going down that route. With all endurance events, you can have resultant pain in the same areas caused by entirely different things. Trying to solve for problem (A) may actually exacerbate problem (B).

Instead, I'd recommend seeing a physical therapist or sports medicine doctor. Both can help you correctly identify what is actually injured and the PT and often the doc can help you identify how it got injured and what you need to change (setup of bike, strength in particular muscle, etc) to prevent it from occuring.

In the meantime, RICE: Rest, Ice, Compression, Elevation. Ice baths aren't fun, but they really do work.

Happy Riding!