Today i set out to do a 5k with the first mile going well but towards the end i felt like my groin on both sides became really tight and it became difficult to put out a good stride. I had to end the run at 2 miles as it became so painful and walk the rest of the way home. Once home my hips/groin on both sides feel really tight. I stretched before running and i always stretch after. I have felt slight pain in the hip before on my left side but it has never prevented me from completing a run before and this was also solved by having a good stretch once i was home in the past. Has anyone an idea What could be causing this and what to do prevent it? Any help would be greatly appreciated. Thanks!