I hope you feel better soon. It is frustrating to endure the pain without knowing what is causing it and be able to put an end to it.
Sometimes, our bodies act in a most peculiar way. the reassuring fact is that your screening came OK.
It could be a transition due to hormones fluctuation.
Starflower oil has double amount of GLA than evening primrose. So, if you are taking 1000mg /day of evening primrose, you only need 500 mg of starflower oil. It will help reduce any inflamation and gently control the hormones.
You are very brave to persevere with your running. This is an added sign of health and strength.