Hip exercises for pain

I’m looking for some ways I can strengthen my hips, and stretch them for mobility at home. I am experiencing pain in my left hip flexor, and have tryouts in 12 days… So any last minute things will help (I know I can’t make a big difference but want to do them for long term fix).
I have access to a 2 lb ball (no throws), a physioball and some Dumbbells

I feel the pain usually when I pull my knee up, to my body.