Sorry to hear you’re experiencing pain and discomfort. Let’s see if we can get this figured out. It sounds like both of you might be over-leveling your pelvis. In general, men usually have a level pelvis to begin with, and they just need to focus on engaging the core. Engaging is different than leveling. When you engage, you should experience just a slight tension in the lower abs. This is comparable to the tension you would feel when you sneeze ... it’s that light! Next time you go on a run, try letting off the leveling of the pelvis a bit. You don’t want to be so tense that you can’t even work in pelvic rotation!
As for the tightness in the shoulders, this could come from having slumped or rounded shouldered posture and then taking on the task of straightening your posture as you run. Lengthen the back of your neck while dropping your shoulders at the same time, while running and throughout your day. This is a practice, and will only change with time. Also, remember that you’re reaching through the crown of your head, which many get confused with the top of the head. The crown is a little towards the back, and is flat. By reaching towards the sky with the crown, the back of your neck will lengthen and it shouldn’t feel like a stressful or tense position.
Hopefully this helps. Please let me know if you still have questions. Happy to help!